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the evidence does not implicate any single pregnancy-related risk factor as a cause of autism, the risk of autism is associated with advanced age in either parent, and with diabetes, bleeding, and use of psychiatric drugs in the mother during pregnancy. the risk is greater with older fathers than with older mothers; two potential explanations are the known increase in mutation burden in older sperm, and the hypothesis that men marry later if they carry genetic liability and show some signs of autism. most professionals believe that race, ethnicity, and socioeconomic background do not affect the occurrence of autism. several other conditions are common in children with autism. they include: genetic disorders. about 1015% of autism cases have an identifiable mendelian (single-gene) condition, chromosome abnormality,

or other genetic syndrome, and asd is associated with several genetic disorders. intellectual disability. the percentage of autistic individuals who also meet criteria for intellectual disability has been reported as anywhere from 25% to 70%, a wide variation illustrating the difficulty of assessing intelligence of individuals on the autism spectrum. in comparison, for pdd-nos the association with intellectual disability is much weaker, and by definition, the diagnosis of asperger's excludes intellectual disability. anxiety disorders are common among children with asd; there are no firm data, but studies have reported prevalences ranging from 11% to 84%. many anxiety disorders have symptoms that are better explained by asd itself, or are hard to distinguish from asd's symptoms. epilepsy, with variations in

risk of epilepsy due to age, cognitive level, and type of language disorder. several metabolic defects, such as phenylketonuria, are associated with autistic symptoms. minor physical anomalies are significantly increased in the autistic population. preempted diagnoses. although the dsm-iv rules out the concurrent diagnosis of many other conditions along with autism, the full criteria for attention deficit hyperactivity disorder (adhd), tourette syndrome, and other of these conditions are often present and these co-occurrent conditions are increasingly accepted. sleep problems affect about two-thirds of individuals with asd at some point in childhood. these most commonly include symptoms of insomnia such as difficulty in falling asleep, frequent nocturnal awakenings, and early morning awakenings. sleep problems

are associated with difficult behaviors and family stress, and are often a focus of clinical attention over and above the primary asd diagnosis. history a few examples of autistic symptoms and treatments were described long before autism was named. the table talk of martin luther, compiled by his notetaker, mathesius, contains the story of a 12-year-old boy who may have been severely autistic. the earliest well-documented case of autism is that of hugh blair of borgue, as detailed in a 1747 court case in which his brother successfully petitioned to annul blair's marriage to gain blair's inheritance. the wild boy of aveyron, a feral child caught in 1798, showed several signs of autism; the medical student jean itard treated him with a behavioral program designed to help him form social attachments and to induce

speech via imitation. the new latin word autismus (english translation autism) was coined by the swiss psychiatrist eugen bleuler in 1910 as he was defining symptoms of schizophrenia. he derived it from the greek word autos (, meaning "self"), and used it to mean morbid self-admiration, referring to "autistic withdrawal of the patient to his fantasies, against which any influence from outside becomes an intolerable disturbance". a soviet child psychiatrist, grunya sukhareva, described a similar syndrome that was published in russian in 1925, and in german in 1926. clinical development and diagnoses the word autism first took its modern sense in 1938 when hans asperger of the vienna university hospital adopted bleuler's terminology autistic psychopaths in a lecture in german about child psychology. asperger

was investigating an asd now known as asperger syndrome, though for various reasons it was not widely recognized as a separate diagnosis until 1981. leo kanner of the johns hopkins hospital first used autism in its modern sense in english when he introduced the label early infantile autism in a 1943 report of 11 children with striking behavioral similarities. almost all the characteristics described in kanner's first paper on the subject, notably "autistic aloneness" and "insistence on sameness", are still regarded as typical of the autistic spectrum of disorders. it is not known whether kanner derived the term independently of asperger. kanner's reuse of autism led to decades of confused terminology like infantile schizophrenia, and child psychiatry's focus on maternal deprivation led to misconceptions of autism

as an infant's response to "refrigerator mothers". starting in the late 1960s autism was established as a separate syndrome. terminology and distinction from schizophrenia as late as the mid-1970s there was little evidence of a genetic role in autism, while in 2007 it was believed to be one of the most heritable psychiatric conditions. although the rise of parent organizations and the destigmatization of childhood asd have affected how asd is viewed, parents continue to feel social stigma in situations where their child's autistic behavior is perceived negatively, and many primary care physicians and medical specialists express some beliefs consistent with outdated autism research. it took until 1980 for the dsm-iii to differentiate autism from childhood schizophrenia. in 1987, the dsm-iii-r provided a checklist

for diagnosing autism. in may 2013, the dsm-5 was released, updating the classification for pervasive developmental disorders. the grouping of disorders, including pdd-nos, autism, asperger syndrome, rett syndrome, and cdd, has been removed and replaced with the general term of autism spectrum disorders. the two categories that exist are impaired social communication and/or interaction, and restricted and/or repetitive behaviors. the internet has helped autistic individuals bypass nonverbal cues and emotional sharing that they find difficult to deal with, and has given them a way to form online communities and work remotely. societal and cultural aspects of autism have developed: some in the community seek a cure, while others believe that autism is simply another way of being. society and culture an autistic

culture has emerged, accompanied by the autistic rights and neurodiversity movements. events include world autism awareness day, autism sunday, autistic pride day, autreat, and others. social-science scholars study those with autism in hopes to learn more about "autism as a culture, transcultural comparisons... and research on social movements." many autistic individuals have been successful in their fields. autism rights movement the autism rights movement is a social movement within the context of disability rights that emphasizes the concept of neurodiversity, viewing the autism spectrum as a result of natural variations in the human brain rather than a disorder to be cured. the autism rights movement advocates for including greater acceptance of autistic behaviors; therapies that focus on coping skills

rather than on imitating the behaviors of those without autism, and the recognition of the autistic community as a minority group. autism rights or neurodiversity advocates believe that the autism spectrum is genetic and should be accepted as a natural expression of the human genome. this perspective is distinct from fringe theories that autism is caused by environmental factors such as vaccines. a common criticism against autistic activists is that the majority of them are "high-functioning" or have asperger syndrome and do not represent the views of "low-functioning" autistic people. employment about half of autistic people are unemployed, and one third of those with graduate degrees may be unemployed. among those who find work, most are employed in sheltered settings working for wages below the national minimum.

while employers state hiring concerns about productivity and supervision, experienced employers of autistic people give positive reports of above average memory and detail orientation as well as a high regard for rules and procedure in autistic employees. a majority of the economic burden of autism is caused by decreased earnings in the job market. some studies also find decreased earning among parents who care for autistic children. references external links 1910s neologisms articles containing video clips communication disorders neurological disorders in children pervasive developmental disorders wikipedia medicine articles ready to translate

albedo (; ) is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that reflects all incident radiation. surface albedo is defined as the ratio of radiosity je to the irradiance ee (flux per unit area) received by a surface. the proportion reflected is not only determined by properties of the surface itself, but also by the spectral and angular distribution of solar radiation reaching the earth's surface. these factors vary with atmospheric composition, geographic location, and time (see position of the sun). while bi-hemispherical reflectance is calculated for a single angle of incidence (i.e., for a given position of the sun), albedo is the directional

integration of reflectance over all solar angles in a given period. the temporal resolution may range from seconds (as obtained from flux measurements) to daily, monthly, or annual averages. unless given for a specific wavelength (spectral albedo), albedo refers to the entire spectrum of solar radiation. due to measurement constraints, it is often given for the spectrum in which most solar energy reaches the surface (between 0.3 and 3 m). this spectrum includes visible light (0.40.7 m), which explains why surfaces with a low albedo appear dark (e.g., trees absorb most radiation), whereas surfaces with a high albedo appear bright (e.g., snow reflects most radiation). albedo is an important concept in climatology, astronomy, and environmental management (e.g., as part of the leadership in energy and environmental

design (leed) program for sustainable rating of buildings). the average albedo of the earth from the upper atmosphere, its planetary albedo, is 3035% because of cloud cover, but widely varies locally across the surface because of different geological and environmental features. the term albedo was introduced into optics by johann heinrich lambert in his 1760 work photometria. terrestrial albedo any albedo in visible light falls within a range of about 0.9 for fresh snow to about 0.04 for charcoal, one of the darkest substances. deeply shadowed cavities can achieve an effective albedo approaching the zero of a black body. when seen from a distance, the ocean surface has a low albedo, as do most forests, whereas desert areas have some of the highest albedos among landforms. most land areas are in an albedo range

of 0.1 to 0.4. the average albedo of earth is about 0.3. this is far higher than for the ocean primarily because of the contribution of clouds. earth's surface albedo is regularly estimated via earth observation satellite sensors such as nasa's modis instruments on board the terra and aqua satellites, and the ceres instrument on the suomi npp and jpss. as the amount of reflected radiation is only measured for a single direction by satellite, not all directions, a mathematical model is used to translate a sample set of satellite reflectance measurements into estimates of directional-hemispherical reflectance and bi-hemispherical reflectance (e.g.,). these calculations are based on the bidirectional reflectance distribution function (brdf), which describes how the reflectance of a given surface depends on the

view angle of the observer and the solar angle. bdrf can facilitate translations of observations of reflectance into albedo. earth's average surface temperature due to its albedo and the greenhouse effect is currently about . if earth were frozen entirely (and hence be more reflective), the average temperature of the planet would drop below . if only the continental land masses became covered by glaciers, the mean temperature of the planet would drop to about . in contrast, if the entire earth was covered by water a so-called ocean planet the average temperature on the planet would rise to almost . in 2021, scientists reported that earth dimmed by ~0.5% over two decades (1998-2017) as measured by earthshine using modern photometric techniques. this may have both been co-caused by climate change as well as

a substantial increase in global warming. however, the link to climate change has not been explored to date and it is unclear whether or not this represents an ongoing trend. white-sky, black-sky, and blue-sky albedo for land surfaces, it has been shown that the albedo at a particular solar zenith angle i can be approximated by the proportionate sum of two terms: the directional-hemispherical reflectance at that solar zenith angle, , sometimes referred to as black-sky albedo, and the bi-hemispherical reflectance, , sometimes referred to as white-sky albedo. with being the proportion of direct radiation from a given solar angle, and being the proportion of diffuse illumination, the actual albedo (also called blue-sky albedo) can then be given as: this formula is important because it allows the albedo to be

calculated for any given illumination conditions from a knowledge of the intrinsic properties of the surface. examples of terrestrial albedo effects illumination albedo is not directly dependent on illumination because changing the amount of incoming light proportionally changes the amount of reflected light, except in circumstances where a change in illumination induces a change in the earth's surface at that location (e.g. through melting of reflective ice). that said, albedo and illumination both vary by latitude. albedo is highest near the poles and lowest in the subtropics, with a local maximum in the tropics. insolation effects the intensity of albedo temperature effects depends on the amount of albedo and the level of local insolation (solar irradiance); high albedo areas in the arctic and antarctic

regions are cold due to low insolation, whereas areas such as the sahara desert, which also have a relatively high albedo, will be hotter due to high insolation. tropical and sub-tropical rainforest areas have low albedo, and are much hotter than their temperate forest counterparts, which have lower insolation. because insolation plays such a big role in the heating and cooling effects of albedo, high insolation areas like the tropics will tend to show a more pronounced fluctuation in local temperature when local albedo changes. arctic regions notably release more heat back into space than what they absorb, effectively cooling the earth. this has been a concern since arctic ice and snow has been melting at higher rates due to higher temperatures, creating regions in the arctic that are notably darker (being

water or ground which is darker color) and reflects less heat back into space. this feedback loop results in a reduced albedo effect. climate and weather albedo affects climate by determining how much radiation a planet absorbs. the uneven heating of earth from albedo variations between land, ice, or ocean surfaces can drive weather. albedotemperature feedback when an area's albedo changes due to snowfall, a snowtemperature feedback results. a layer of snowfall increases local albedo, reflecting away sunlight, leading to local cooling. in principle, if no outside temperature change affects this area (e.g., a warm air mass), the raised albedo and lower temperature would maintain the current snow and invite further snowfall, deepening the snowtemperature feedback. however, because local weather is dynamic due

to the change of seasons, eventually warm air masses and a more direct angle of sunlight (higher insolation) cause melting. when the melted area reveals surfaces with lower albedo, such as grass, soil, or ocean, the effect is reversed: the darkening surface lowers albedo, increasing local temperatures, which induces more melting and thus reducing the albedo further, resulting in still more heating. snow snow albedo is highly variable, ranging from as high as 0.9 for freshly fallen snow, to about 0.4 for melting snow, and as low as 0.2 for dirty snow. over antarctica snow albedo averages a little more than 0.8. if a marginally snow-covered area warms, snow tends to melt, lowering the albedo, and hence leading to more snowmelt because more radiation is being absorbed by the snowpack (the icealbedo positive feedback). just

as fresh snow has a higher albedo than does dirty snow, the albedo of snow-covered sea ice is far higher than that of sea water. sea water absorbs more solar radiation than would the same surface covered with reflective snow. when sea ice melts, either due to a rise in sea temperature or in response to increased solar radiation from above, the snow-covered surface is reduced, and more surface of sea water is exposed, so the rate of energy absorption increases. the extra absorbed energy heats the sea water, which in turn increases the rate at which sea ice melts. as with the preceding example of snowmelt, the process of melting of sea ice is thus another example of a positive feedback. both positive feedback loops have long been recognized as important for global warming. cryoconite, powdery windblown dust containing

soot, sometimes reduces albedo on glaciers and ice sheets. the dynamical nature of albedo in response to positive feedback, together with the effects of small errors in the measurement of albedo, can lead to large errors in energy estimates. because of this, in order to reduce the error of energy estimates, it is important to measure the albedo of snow-covered areas through remote sensing techniques rather than applying a single value for albedo over broad regions. small-scale effects albedo works on a smaller scale, too. in sunlight, dark clothes absorb more heat and light-coloured clothes reflect it better, thus allowing some control over body temperature by exploiting the albedo effect of the colour of external clothing. solar photovoltaic effects albedo can affect the electrical energy output of solar

photovoltaic devices. for example, the effects of a spectrally responsive albedo are illustrated by the differences between the spectrally weighted albedo of solar photovoltaic technology based on hydrogenated amorphous silicon (a-si:h) and crystalline silicon (c-si)-based compared to traditional spectral-integrated albedo predictions. research showed impacts of over 10%. more recently, the analysis was extended to the effects of spectral bias due to the specular reflectivity of 22 commonly occurring surface materials (both human-made and natural) and analyzes the albedo effects on the performance of seven photovoltaic materials covering three common photovoltaic system topologies: industrial (solar farms), commercial flat rooftops and residential pitched-roof applications. trees because forests generally have

a low albedo, (the majority of the ultraviolet and visible spectrum is absorbed through photosynthesis), some scientists have suggested that greater heat absorption by trees could offset some of the carbon benefits of afforestation (or offset the negative climate impacts of deforestation). in the case of evergreen forests with seasonal snow cover albedo reduction may be great enough for deforestation to cause a net cooling effect. trees also impact climate in extremely complicated ways through evapotranspiration. the water vapor causes cooling on the land surface, causes heating where it condenses, acts a strong greenhouse gas, and can increase albedo when it condenses into clouds. scientists generally treat evapotranspiration as a net cooling impact, and the net climate impact of albedo and evapotranspiration

changes from deforestation depends greatly on local climate. in seasonally snow-covered zones, winter albedos of treeless areas are 10% to 50% higher than nearby forested areas because snow does not cover the trees as readily. deciduous trees have an albedo value of about 0.15 to 0.18 whereas coniferous trees have a value of about 0.09 to 0.15. variation in summer albedo across both forest types is associated with maximum rates of photosynthesis because plants with high growth capacity display a greater fraction of their foliage for direct interception of incoming radiation in the upper canopy. the result is that wavelengths of light not used in photosynthesis are more likely to be reflected back to space rather than being absorbed by other surfaces lower in the canopy. studies by the hadley centre have investigated

the relative (generally warming) effect of albedo change and (cooling) effect of carbon sequestration on planting forests. they found that new forests in tropical and midlatitude areas tended to cool; new forests in high latitudes (e.g., siberia) were neutral or perhaps warming. water water reflects light very differently from typical terrestrial materials. the reflectivity of a water surface is calculated using the fresnel equations. at the scale of the wavelength of light even wavy water is always smooth so the light is reflected in a locally specular manner (not diffusely). the glint of light off water is a commonplace effect of this. at small angles of incident light, waviness results in reduced reflectivity because of the steepness of the reflectivity-vs.-incident-angle curve and a locally increased average

incident angle. although the reflectivity of water is very low at low and medium angles of incident light, it becomes very high at high angles of incident light such as those that occur on the illuminated side of earth near the terminator (early morning, late afternoon, and near the poles). however, as mentioned above, waviness causes an appreciable reduction. because light specularly reflected from water does not usually reach the viewer, water is usually considered to have a very low albedo in spite of its high reflectivity at high angles of incident light. note that white caps on waves look white (and have high albedo) because the water is foamed up, so there are many superimposed bubble surfaces which reflect, adding up their reflectivities. fresh 'black' ice exhibits fresnel reflection. snow on top of

this sea ice increases the albedo to 0.9. clouds cloud albedo has substantial influence over atmospheric temperatures. different types of clouds exhibit different reflectivity, theoretically ranging in albedo from a minimum of near 0 to a maximum approaching 0.8. "on any given day, about half of earth is covered by clouds, which reflect more sunlight than land and water. clouds keep earth cool by reflecting sunlight, but they can also serve as blankets to trap warmth." albedo and climate in some areas are affected by artificial clouds, such as those created by the contrails of heavy commercial airliner traffic. a study following the burning of the kuwaiti oil fields during iraqi occupation showed that temperatures under the burning oil fires were as much as colder than temperatures several miles away under

clear skies. aerosol effects aerosols (very fine particles/droplets in the atmosphere) have both direct and indirect effects on earth's radiative balance. the direct (albedo) effect is generally to cool the planet; the indirect effect (the particles act as cloud condensation nuclei and thereby change cloud properties) is less certain. as per spracklen et al. the effects are: aerosol direct effect. aerosols directly scatter and absorb radiation. the scattering of radiation causes atmospheric cooling, whereas absorption can cause atmospheric warming. aerosol indirect effect. aerosols modify the properties of clouds through a subset of the aerosol population called cloud condensation nuclei. increased nuclei concentrations lead to increased cloud droplet number concentrations, which in turn leads to increased

cloud albedo, increased light scattering and radiative cooling (first indirect effect), but also leads to reduced precipitation efficiency and increased lifetime of the cloud (second indirect effect). in extremely polluted cities like delhi, aerosol pollutants influence local weather and induce an urban cool island effect during the day. black carbon another albedo-related effect on the climate is from black carbon particles. the size of this effect is difficult to quantify: the intergovernmental panel on climate change estimates that the global mean radiative forcing for black carbon aerosols from fossil fuels is +0.2 w m2, with a range +0.1 to +0.4 w m2. black carbon is a bigger cause of the melting of the polar ice cap in the arctic than carbon dioxide due to its effect on the albedo. human activities human

activities (e.g., deforestation, farming, and urbanization) change the albedo of various areas around the globe. however, quantification of this effect on the global scale is difficult, further study is required to determine anthropogenic effects. albedo in astronomy in astronomy, the term albedo can be defined in several different ways, depending upon the application and the wavelength of electromagnetic radiation involved. optical or visual albedo the albedos of planets, satellites and minor planets such as asteroids can be used to infer much about their properties. the study of albedos, their dependence on wavelength, lighting angle ("phase angle"), and variation in time composes a major part of the astronomical field of photometry. for small and far objects that cannot be resolved by telescopes, much of

what we know comes from the study of their albedos. for example, the absolute albedo can indicate the surface ice content of outer solar system objects, the variation of albedo with phase angle gives information about regolith properties, whereas unusually high radar albedo is indicative of high metal content in asteroids. enceladus, a moon of saturn, has one of the highest known optical albedos of any body in the solar system, with an albedo of 0.99. another notable high-albedo body is eris, with an albedo of 0.96. many small objects in the outer solar system and asteroid belt have low albedos down to about 0.05. a typical comet nucleus has an albedo of 0.04. such a dark surface is thought to be indicative of a primitive and heavily space weathered surface containing some organic compounds. the overall albedo

of the moon is measured to be around 0.14, but it is strongly directional and non-lambertian, displaying also a strong opposition effect. although such reflectance properties are different from those of any terrestrial terrains, they are typical of the regolith surfaces of airless solar system bodies. two common optical albedos that are used in astronomy are the (v-band) geometric albedo (measuring brightness when illumination comes from directly behind the observer) and the bond albedo (measuring total proportion of electromagnetic energy reflected). their values can differ significantly, which is a common source of confusion. in detailed studies, the directional reflectance properties of astronomical bodies are often expressed in terms of the five hapke parameters which semi-empirically describe the variation

of albedo with phase angle, including a characterization of the opposition effect of regolith surfaces. one of these five parameters is yet another type of albedo called the single-scattering albedo. it is used to define scattering of electromagnetic waves on small particles. it depends on properties of the material (refractive index), the size of the particle, and the wavelength of the incoming radiation. an important relationship between an object's astronomical (geometric) albedo, absolute magnitude and diameter is given by: where is the astronomical albedo, is the diameter in kilometers, and is the absolute magnitude. radar albedo in planetary radar astronomy, a microwave (or radar) pulse is transmitted toward a planetary target (e.g. moon, asteroid, etc.) and the echo from the target is measured. in

most instances, the transmitted pulse is circularly polarized and the received pulse is measured in the same sense of polarization as the transmitted pulse (sc) and the opposite sense (oc). the echo power is measured in terms of radar cross-section, , , or (total power, sc + oc) and is equal to the cross-sectional area of a metallic sphere (perfect reflector) at the same distance as the target that would return the same echo power. those components of the received echo that return from first-surface reflections (as from a smooth or mirror-like surface) are dominated by the oc component as there is a reversal in polarization upon reflection. if the surface is rough at the wavelength scale or there is significant penetration into the regolith, there will be a significant sc component in the echo caused by multiple

scattering. for most objects in the solar system, the oc echo dominates and the most commonly reported radar albedo parameter is the (normalized) oc radar albedo (often shortened to radar albedo): where the denominator is the effective cross-sectional area of the target object with mean radius, . a smooth metallic sphere would have . radar albedos of solar system objects the values reported for the moon, mercury, mars, venus, and comet p/2005 jq5 are derived from the total (oc+sc) radar albedo reported in those references. relationship to surface bulk density in the event that most of the echo is from first surface reflections ( or so), the oc radar albedo is a first-order approximation of the fresnel reflection coefficient (aka reflectivity) and can be used to estimate the bulk density of a planetary surface

to a depth of a meter or so (a few wavelengths of the radar wavelength which is typically at the decimeter scale) using the following empirical relationships: . see also cool roof daisyworld emissivity exitance global dimming irradiance kirchhoff's law of thermal radiation opposition surge polar see-saw radar astronomy solar radiation management references external links albedo project albedo encyclopedia of earth nasa modis brdf/albedo product site ocean surface albedo look-up-table surface albedo derived from meteosat observations a discussion of lunar albedos reflectivity of metals (chart) land surface effects on climate climate change feedbacks climate forcing climatology electromagnetic radiation radiometry scattering, absorption and radiative transfer (optics) radiation 1760s

a, or a, is the first letter and the first vowel of the modern english alphabet and the iso basic latin alphabet. its name in english is a (pronounced ), plural aes. it is similar in shape to the ancient greek letter alpha, from which it derives. the uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. the lowercase version can be written in two forms: the double-storey a and single-storey . the latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type. in the english grammar, "a", and its variant "an", are indefinite articles. history the earliest certain ancestor of "a" is aleph (also written 'aleph), the first letter of the phoenician alphabet, which consisted entirely

of consonants (for that reason, it is also called an abjad to distinguish it from a true alphabet). in turn, the ancestor of aleph may have been a pictogram of an ox head in proto-sinaitic script influenced by egyptian hieroglyphs, styled as a triangular head with two horns extended. when the ancient greeks adopted the alphabet, they had no use for a letter to represent the glottal stopthe consonant sound that the letter denoted in phoenician and other semitic languages, and that was the first phoneme of the phoenician pronunciation of the letterso they used their version of the sign to represent the vowel , and called it by the similar name of alpha. in the earliest greek inscriptions after the greek dark ages, dating to the 8th century bc, the letter rests upon its side, but in the greek alphabet of later

times it generally resembles the modern capital letter, although many local varieties can be distinguished by the shortening of one leg, or by the angle at which the cross line is set. the etruscans brought the greek alphabet to their civilization in the italian peninsula and left the letter unchanged. the romans later adopted the etruscan alphabet to write the latin language, and the resulting letter was preserved in the latin alphabet that would come to be used to write many languages, including english. typographic variants during roman times, there were many variant forms of the letter "a". first was the monumental or lapidary style, which was used when inscribing on stone or other "permanent" media. there was also a cursive style used for everyday or utilitarian writing, which was done on more perishable

surfaces. due to the "perishable" nature of these surfaces, there are not as many examples of this style as there are of the monumental, but there are still many surviving examples of different types of cursive, such as majuscule cursive, minuscule cursive, and semicursive minuscule. variants also existed that were intermediate between the monumental and cursive styles. the known variants include the early semi-uncial, the uncial, and the later semi-uncial. at the end of the roman empire (5th century ad), several variants of the cursive minuscule developed through western europe. among these were the semicursive minuscule of italy, the merovingian script in france, the visigothic script in spain, and the insular or anglo-irish semi-uncial or anglo-saxon majuscule of great britain. by the 9th century, the caroline

script, which was very similar to the present-day form, was the principal form used in book-making, before the advent of the printing press. this form was derived through a combining of prior forms. 15th-century italy saw the formation of the two main variants that are known today. these variants, the italic and roman forms, were derived from the caroline script version. the italic form, also called script a, is used in most current handwriting; it consists of a circle and vertical stroke on the right (""). this slowly developed from the fifth-century form resembling the greek letter tau in the hands of medieval irish and english writers. the roman form is used in most printed material; it consists of a small loop with an arc over it ("a"). both derive from the majuscule (capital) form. in greek handwriting,

it was common to join the left leg and horizontal stroke into a single loop, as demonstrated by the uncial version shown. many fonts then made the right leg vertical. in some of these, the serif that began the right leg stroke developed into an arc, resulting in the printed form, while in others it was dropped, resulting in the modern handwritten form. graphic designers refer to the italic and roman forms as "single decker a" and "double decker a" respectively. italic type is commonly used to mark emphasis or more generally to distinguish one part of a text from the rest (set in roman type). there are some other cases aside from italic type where script a (""), also called latin alpha, is used in contrast with latin "a" (such as in the international phonetic alphabet). use in writing systems english in modern

english orthography, the letter represents at least seven different vowel sounds: the near-open front unrounded vowel as in pad; the open back unrounded vowel as in father, which is closer to its original latin and greek sound; the diphthong as in ace and major (usually when is followed by one, or occasionally two, consonants and then another vowel letter) this results from middle english lengthening followed by the great vowel shift; the modified form of the above sound that occurs before , as in square and mary; the rounded vowel of water; the shorter rounded vowel (not present in general american) in was and what; a schwa, in many unstressed syllables, as in about, comma, solar. the double sequence does not occur in native english words, but is found in some words derived from foreign languages such as aaron

and aardvark. however, occurs in many common digraphs, all with their own sound or sounds, particularly , , , , and . is the third-most-commonly used letter in english (after and ) and french, the second most common in spanish, and the most common in portuguese. about 8.167% of letters used in english texts tend to be ; the number is around 7.636% in french, 11.525% in spanish, and 14.634% for portuguese. other languages in most languages that use the latin alphabet, denotes an open unrounded vowel, such as , , or . an exception is saanich, in which (and the glyph a) stands for a close-mid front unrounded vowel . other systems in phonetic and phonemic notation: in the international phonetic alphabet, is used for the open front unrounded vowel, is used for the open central unrounded vowel, and is used for

the open back unrounded vowel. in x-sampa, is used for the open front unrounded vowel and is used for the open back unrounded vowel. other uses in algebra, the letter a along with various other letters of the alphabet is often used to denote a variable, with various conventional meanings in different areas of mathematics. moreover, in 1637, rene descartes "invented the convention of representing unknowns in equations by x, y, and z, and knowns by a, b, and c", and this convention is still often followed, especially in elementary algebra. in geometry, capital a, b, c etc. are used to denote segments, lines, rays, etc. a capital a is also typically used as one of the letters to represent an angle in a triangle, the lowercase a representing the side opposite angle a. "a" is often used to denote something or

someone of a better or more prestigious quality or status: a-, a or a+, the best grade that can be assigned by teachers for students' schoolwork; "a grade" for clean restaurants; a-list celebrities, etc. such associations can have a motivating effect, as exposure to the letter a has been found to improve performance, when compared with other letters. "a" is used as a prefix on some words, such as asymmetry, to mean "not" or "without" (from greek). in english grammar, "a", and its variant "an", is an indefinite article, used to introduce noun phrases. finally, the letter a is used to denote size, as in a narrow size shoe, or a small cup size in a brassiere. related characters descendants and related characters in the latin alphabet : latin ae ligature a with diacritics: a a a a a a a a a a a a a a a a

a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a phonetic alphabet symbols related to a (the international phonetic alphabet only uses lowercase, but uppercase forms are used in some other writing systems): : latin letter alpha / script a, which represents an open back unrounded vowel in the ipa : latin small letter alpha with retroflex hook : turned a, which represents a near-open central vowel in the ipa : turned v (also called a wedge, a caret, or a hat), which represents an open-mid back unrounded vowel in the ipa : turned alpha / script a, which represents an open back rounded vowel in the ipa : modifier letter small turned alpha : small capital a, an obsolete or non-standard symbol in the international phonetic alphabet used to represent

various sounds (mainly open vowels) a a : modifier letters are used in the uralic phonetic alphabet (upa) (sometimes encoded with unicode subscripts and superscripts) a : subscript small a is used in indo-european studies : small letter a reversed-schwa is used in the teuthonista phonetic transcription system : glottal a, used in the transliteration of ugaritic derived signs, symbols and abbreviations : an ordinal indicator a : angstrom sign : a turned capital letter a, used in predicate logic to specify universal quantification ("for all") @ : at sign : argentine austral ancestors and siblings in other alphabets : semitic letter aleph, from which the following symbols originally derive : greek letter alpha, from which the following letters derive : cyrillic letter a : coptic letter alpha : old

italic a, which is the ancestor of modern latin a : runic letter ansuz, which probably derives from old italic a : gothic letter aza/asks : armenian letter ayb computing codes 1 other representations notes footnotes references external links history of the alphabet iso basic latin letters vowel letters

alabama () is a state in the southeastern region of the united states, bordered by tennessee to the north; georgia to the east; florida and the gulf of mexico to the south; and mississippi to the west. alabama is the 30th largest by area and the 24th-most populous of the u.s. states. with a total of of inland waterways, alabama has among the most of any state. alabama is nicknamed the yellowhammer state, after the state bird. alabama is also known as the "heart of dixie" and the "cotton state". the state tree is the longleaf pine, and the state flower is the camellia. alabama's capital is montgomery, and its largest city by population and area is huntsville. its oldest city is mobile, founded by french colonists in 1702 as the capital of french louisiana. greater birmingham is alabama's largest metropolitan area

and its economic center. originally home to many native tribes, present-day alabama was a spanish territory beginning in the sixteenth century until the french acquired it in the early eighteenth century. the british won the territory in 1763 until losing it in the american revolutionary war. spain held mobile as part of spanish west florida until 1813. in december 1819, alabama was recognized as a state. during the antebellum period, alabama was a major producer of cotton, and widely used african american slave labor. in 1861, the state seceded from the united states to become part of the confederate states of america, with montgomery acting as its first capital, and rejoined the union in 1868. following the american civil war, alabama would suffer decades of economic hardship, in part due to agriculture and

a few cash crops being the main driver of the states economy. similar to other former slave states, alabamian legislators employed jim crow laws to disenfranchise and discriminate against african americans from the late 19th century up until the 1960s. in the early 20th century, despite the growth of major industries and urban centers, white rural interests dominated the state legislature through the mid-20th century. during this time, urban interests and african americans were markedly under-represented. high-profile events such as the selma to montgomery march made the state a major focal point of the civil rights movement in the 1950s and 1960s. during and after world war ii, alabama grew as the state's economy diversified with new industries. nasa's marshall space flight center in huntsville would help

alabama's economic growth in the mid-to-late 20th century, by developing an aerospace industry. alabama's economy in the 21st century is based on automotive, finance, tourism, manufacturing, aerospace, mineral extraction, healthcare, education, retail, and technology. the state's geography is diverse, with the north dominated by the mountainous tennessee valley and the south by mobile bay, a historically significant port. politically, as part of the deep south, alabama is predominantly a conservative state, and culturally is known for its southern culture. within alabama, american football, particularly at the college level at schools such as the university of alabama, auburn university, alabama a&m university, alabama state university, troy university, the university of south alabama, and jacksonville state

university, play a major part of the state's culture. etymology the european-american naming of the alabama river and state was derived from the alabama people, a muskogean-speaking tribe whose members lived just below the confluence of the coosa and tallapoosa rivers on the upper reaches of the river. in the alabama language, the word for a person of alabama lineage is (or variously or in different dialects; the plural form is ). the suggestion that "alabama" was borrowed from the choctaw language is unlikely. the word's spelling varies significantly among historical sources. the first usage appears in three accounts of the hernando de soto expedition of 1540: garcilaso de la vega used , while the knight of elvas and rodrigo ranjel wrote alibamu and limamu, respectively, in transliterations of the term. as

early as 1702, the french called the tribe the , with french maps identifying the river as . other spellings of the name have included alibamu, alabamo, albama, alebamon, alibama, alibamou, alabamu, allibamou. and possibly alabahmu. the use of state names derived from native american languages is common in the u.s.; an estimated 27 states have names of native american origin. sources disagree on the word's meaning. some scholars suggest the word comes from the choctaw (meaning 'plants' or 'weeds') and (meaning 'to cut', 'to trim', or 'to gather'). the meaning may have been 'clearers of the thicket' or 'herb gatherers', referring to clearing land for cultivation or collecting medicinal plants. the state has numerous place names of native american origin. however, there are no correspondingly similar words in

the alabama language. an 1842 article in the jacksonville republican proposed it meant 'here we rest'. this notion was popularized in the 1850s through the writings of alexander beaufort meek. experts in the muskogean languages have not found any evidence to support such a translation. history pre-european settlement indigenous peoples of varying cultures lived in the area for thousands of years before the advent of european colonization. trade with the northeastern tribes by the ohio river began during the burial mound period (1000bce700ce) and continued until european contact. the agrarian mississippian culture covered most of the state from 1000 to 1600 ce, with one of its major centers built at what is now the moundville archaeological site in moundville, alabama. this is the second-largest complex of

the classic middle mississippian era, after cahokia in present-day illinois, which was the center of the culture. analysis of artifacts from archaeological excavations at moundville were the basis of scholars' formulating the characteristics of the southeastern ceremonial complex (secc). contrary to popular belief, the secc appears to have no direct links to mesoamerican culture, but developed independently. the ceremonial complex represents a major component of the religion of the mississippian peoples; it is one of the primary means by which their religion is understood. among the historical tribes of native american people living in present-day alabama at the time of european contact were the cherokee, an iroquoian language people; and the muskogean-speaking alabama (alibamu), chickasaw, choctaw, creek, and

koasati. while part of the same large language family, the muskogee tribes developed distinct cultures and languages. european settlement the spanish were the first europeans to reach alabama during their exploration of north america in the 16th century. the expedition of hernando de soto passed through mabila and other parts of the state in 1540. more than 160 years later, the french founded the region's first european settlement at old mobile in 1702. the city was moved to the current site of mobile in 1711. this area was claimed by the french from 1702 to 1763 as part of la louisiane. after the french lost to the british in the seven years' war, it became part of british west florida from 1763 to 1783. after the united states victory in the american revolutionary war, the territory was divided between the

united states and spain. the latter retained control of this western territory from 1783 until the surrender of the spanish garrison at mobile to u.s. forces on april 13, 1813. thomas bassett, a loyalist to the british monarchy during the revolutionary era, was one of the earliest white settlers in the state outside mobile. he settled in the tombigbee district during the early 1770s. the district's boundaries were roughly limited to the area within a few miles of the tombigbee river and included portions of what is today southern clarke county, northernmost mobile county, and most of washington county. what is now the counties of baldwin and mobile became part of spanish west florida in 1783, part of the independent republic of west florida in 1810, and was finally added to the mississippi territory in 1812.

most of what is now the northern two-thirds of alabama was known as the yazoo lands beginning during the british colonial period. it was claimed by the province of georgia from 1767 onwards. following the revolutionary war, it remained a part of georgia, although heavily disputed. with the exception of the area around mobile and the yazoo lands, what is now the lower one-third of alabama was made part of the mississippi territory when it was organized in 1798. the yazoo lands were added to the territory in 1804, following the yazoo land scandal. spain kept a claim on its former spanish west florida territory in what would become the coastal counties until the adamsonis treaty officially ceded it to the united states in 1819. early 19th century before mississippi's admission to statehood on december 10, 1817,

the more sparsely settled eastern half of the territory was separated and named the alabama territory. the united states congress created the alabama territory on march 3, 1817. st. stephens, now abandoned, served as the territorial capital from 1817 to 1819. alabama was admitted as the 22nd state on december 14, 1819, with congress selecting huntsville as the site for the first constitutional convention. from july5 to august 2, 1819, delegates met to prepare the new state constitution. huntsville served as temporary capital from 1819 to 1820, when the seat of government moved to cahaba in dallas county. cahaba, now a ghost town, was the first permanent state capital from 1820 to 1825. the alabama fever land rush was underway when the state was admitted to the union, with settlers and land speculators pouring

into the state to take advantage of fertile land suitable for cotton cultivation. part of the frontier in the 1820s and 1830s, its constitution provided for universal suffrage for white men. southeastern planters and traders from the upper south brought slaves with them as the cotton plantations in alabama expanded. the economy of the central black belt (named for its dark, productive soil) was built around large cotton plantations whose owners' wealth grew mainly from slave labor. the area also drew many poor, disenfranchised people who became subsistence farmers. alabama had an estimated population of under 10,000 people in 1810, but it increased to more than 300,000 people by 1830. most native american tribes were completely removed from the state within a few years of the passage of the indian removal act

by congress in 1830. from 1826 to 1846, tuscaloosa served as alabama's capital. on january 30, 1846, the alabama legislature announced it had voted to move the capital city from tuscaloosa to montgomery. the first legislative session in the new capital met in december 1847. a new capitol building was erected under the direction of stephen decatur button of philadelphia. the first structure burned down in 1849, but was rebuilt on the same site in 1851. this second capitol building in montgomery remains to the present day. it was designed by barachias holt of exeter, maine. civil war and reconstruction by 1860, the population had increased to 964,201 people, of which nearly half, 435,080, were enslaved african americans, and 2,690 were free people of color. on january 11, 1861, alabama declared its secession

from the union. after remaining an independent republic for a few days, it joined the confederate states of america. the confederacy's capital was initially at montgomery. alabama was heavily involved in the american civil war. although comparatively few battles were fought in the state, alabama contributed about 120,000 soldiers to the war effort. a company of cavalry soldiers from huntsville, alabama, joined nathan bedford forrest's battalion in hopkinsville, kentucky. the company wore new uniforms with yellow trim on the sleeves, collar and coattails. this led to them being greeted with "yellowhammer", and the name later was applied to all alabama troops in the confederate army. alabama's slaves were freed by the 13th amendment in 1865. alabama was under military rule from the end of the war in may 1865

until its official restoration to the union in 1868. from 1867 to 1874, with most white citizens barred temporarily from voting and freedmen enfranchised, many african americans emerged as political leaders in the state. alabama was represented in congress during this period by three african-american congressmen: jeremiah haralson, benjamin s. turner, and james t. rapier. following the war, the state remained chiefly agricultural, with an economy tied to cotton. during reconstruction, state legislators ratified a new state constitution in 1868 which created the state's first public school system and expanded women's rights. legislators funded numerous public road and railroad projects, although these were plagued with allegations of fraud and misappropriation. organized insurgent, resistance groups tried to

suppress the freedmen and republicans. besides the short-lived original ku klux klan, these included the pale faces, knights of the white camellia, red shirts, and the white league. reconstruction in alabama ended in 1874, when the democrats regained control of the legislature and governor's office through an election dominated by fraud and violence. they wrote another constitution in 1875, and the legislature passed the blaine amendment, prohibiting public money from being used to finance religious-affiliated schools. the same year, legislation was approved that called for racially segregated schools. railroad passenger cars were segregated in 1891. 20th century the new 1901 constitution of alabama included provisions for voter registration that effectively disenfranchised large portions of the population,

including nearly all african americans and native americans, and tens of thousands of poor european americans, through making voter registration difficult, requiring a poll tax and literacy test. the 1901 constitution required racial segregation of public schools. by 1903 only 2,980 african americans were registered in alabama, although at least 74,000 were literate. this compared to more than 181,000 african americans eligible to vote in 1900. the numbers dropped even more in later decades. the state legislature passed additional racial segregation laws related to public facilities into the 1950s: jails were segregated in 1911; hospitals in 1915; toilets, hotels, and restaurants in 1928; and bus stop waiting rooms in 1945. while the planter class had persuaded poor whites to vote for this legislative effort

to suppress black voting, the new restrictions resulted in their disenfranchisement as well, due mostly to the imposition of a cumulative poll tax. by 1941, whites constituted a slight majority of those disenfranchised by these laws: 600,000 whites vs. 520,000 african-americans. nearly all blacks had lost the ability to vote. despite numerous legal challenges which succeeded in overturning certain provisions, the state legislature would create new ones to maintain disenfranchisement. the exclusion of blacks from the political system persisted until after passage of federal civil rights legislation in 1965 to enforce their constitutional rights as citizens. the rural-dominated alabama legislature consistently underfunded schools and services for the disenfranchised african americans, but it did not relieve them

of paying taxes. partially as a response to chronic underfunding of education for african americans in the south, the rosenwald fund began funding the construction of what came to be known as rosenwald schools. in alabama these schools were designed and the construction partially financed with rosenwald funds, which paid one-third of the construction costs. the fund required the local community and state to raise matching funds to pay the rest. black residents effectively taxed themselves twice, by raising additional monies to supply matching funds for such schools, which were built in many rural areas. they often donated land and labor as well. beginning in 1913, the first 80 rosenwald schools were built in alabama for african-american children. a total of 387 schools, seven teachers' houses, and several vocational

buildings were completed by 1937 in the state. several of the surviving school buildings in the state are now listed on the national register of historic places. continued racial discrimination and lynchings, agricultural depression, and the failure of the cotton crops due to boll weevil infestation led tens of thousands of african americans from rural alabama and other states to seek opportunities in northern and midwestern cities during the early decades of the 20th century as part of the great migration out of the south. reflecting this emigration, the population growth rate in alabama (see "historical populations" table below) dropped by nearly half from 1910 to 1920. at the same time, many rural people migrated to the city of birmingham to work in new industrial jobs. birmingham experienced such rapid

growth it was called the "magic city". by 1920, birmingham was the 36th-largest city in the united states. heavy industry and mining were the basis of its economy. its residents were under-represented for decades in the state legislature, which refused to redistrict after each decennial census according to population changes, as it was required by the state constitution. this did not change until the late 1960s following a lawsuit and court order. industrial development related to the demands of world war ii brought a level of prosperity to the state not seen since before the civil war. rural workers poured into the largest cities in the state for better jobs and a higher standard of living. one example of this massive influx of workers occurred in mobile. between 1940 and 1943, more than 89,000 people moved

into the city to work for war-related industries. cotton and other cash crops faded in importance as the state developed a manufacturing and service base. despite massive population changes in the state from 1901 to 1961, the rural-dominated legislature refused to reapportion house and senate seats based on population, as required by the state constitution to follow the results of decennial censuses. they held on to old representation to maintain political and economic power in agricultural areas. one result was that jefferson county, containing birmingham's industrial and economic powerhouse, contributed more than one-third of all tax revenue to the state, but did not receive a proportional amount in services. urban interests were consistently underrepresented in the legislature. a 1960 study noted that because

of rural domination, "a minority of about 25% of the total state population is in majority control of the alabama legislature." in the united states supreme court cases of baker v. carr (1962) and reynolds v. sims (1964), the court ruled that the principle of "one man, one vote" needed to be the basis of both houses of state legislatures, and that their districts had to be based on population rather than geographic counties. in 1972, for the first time since 1901, the legislature completed the congressional redistricting based on the decennial census. this benefited the urban areas that had developed, as well as all in the population who had been underrepresented for more than sixty years. other changes were made to implement representative state house and senate districts. african americans continued to press

in the 1950s and 1960s to end disenfranchisement and segregation in the state through the civil rights movement, including legal challenges. in 1954, the u.s. supreme court ruled in brown v. board of education that public schools had to be desegregated, but alabama was slow to comply. during the 1960s, under governor george wallace, alabama resisted compliance with federal demands for desegregation. the civil rights movement had notable events in alabama, including the montgomery bus boycott (19551956), freedom rides in 1961, and 1965 selma to montgomery marches. these contributed to congressional passage and enactment of the civil rights act of 1964 and voting rights act of 1965 by the u.s. congress. legal segregation ended in the states in 1964, but jim crow customs often continued until specifically challenged

in court. according to the new york times, by 2017, many of alabama's african-americans were living in alabama's cities such as birmingham and montgomery. also, the black belt region across central alabama "is home to largely poor counties that are predominantly african-american. these counties include dallas, lowndes, marengo and perry." alabama has made some changes since the late 20th century and has used new types of voting to increase representation. in the 1980s, an omnibus redistricting case, dillard v. crenshaw county, challenged the at-large voting for representative seats of 180 alabama jurisdictions, including counties and school boards. at-large voting had diluted the votes of any minority in a county, as the majority tended to take all seats. despite african americans making up a significant minority

in the state, they had been unable to elect any representatives in most of the at-large jurisdictions. as part of settlement of this case, five alabama cities and counties, including chilton county, adopted a system of cumulative voting for election of representatives in multi-seat jurisdictions. this has resulted in more proportional representation for voters. in another form of proportional representation, 23 jurisdictions use limited voting, as in conecuh county. in 1982, limited voting was first tested in conecuh county. together use of these systems has increased the number of african americans and women being elected to local offices, resulting in governments that are more representative of their citizens. beginning in the 1960s, the state's economy shifted away from its traditional lumber, steel, and

textile industries because of increased foreign competition. steel jobs, for instance, declined from 46,314 in 1950 to 14,185 in 2011. however, the state, particularly huntsville, benefited from the opening of the george c. marshall space flight center in 1960, a major facility in the development of the saturn rocket program and the space shuttle. technology and manufacturing industries, such as automobile assembly, replaced some the state's older industries in the late twentieth century, but the state's economy and growth lagged behind other states in the area, such as georgia and florida. 21st century in 2001, alabama supreme court chief justice roy moore installed a statue of the ten commandments in the capitol in montgomery. in 2002, the 11th us circuit court ordered the statue removed, but moore refused

to follow the court order, which led to protests around the capitol in favor of keeping the monument. the monument was removed in august 2003. a few natural disasters have occurred in the state in the twenty-first century. in 2004, hurricane ivan, a category 3 storm upon landfall, struck the state and caused over $18 billion of damage. it was among the most destructive storms to strike the state in its modern history. a super outbreak of 62 tornadoes hit the state in april 2011 and killed 238 people, devastating many communities. geography alabama is the thirtieth-largest state in the united states with of total area: 3.2% of the area is water, making alabama 23rd in the amount of surface water, also giving it the second-largest inland waterway system in the united states. about three-fifths of the land area

is part of the gulf coastal plain, a gentle plain with a general descent towards the mississippi river and the gulf of mexico. the north alabama region is mostly mountainous, with the tennessee river cutting a large valley and creating numerous creeks, streams, rivers, mountains, and lakes. alabama is bordered by the states of tennessee to the north, georgia to the east, florida to the south, and mississippi to the west. alabama has coastline at the gulf of mexico, in the extreme southern edge of the state. the state ranges in elevation from sea level at mobile bay to more than in the northeast, to mount cheaha at . alabama's land consists of of forest or 67% of the state's total land area. suburban baldwin county, along the gulf coast, is the largest county in the state in both land area and water area. areas

in alabama administered by the national park service include horseshoe bend national military park near alexander city; little river canyon national preserve near fort payne; russell cave national monument in bridgeport; tuskegee airmen national historic site in tuskegee; and tuskegee institute national historic site near tuskegee. additionally, alabama has four national forests: conecuh, talladega, tuskegee, and william b. bankhead. alabama also contains the natchez trace parkway, the selma to montgomery national historic trail, and the trail of tears national historic trail. notable natural wonders include: the "natural bridge" rock, the longest natural bridge east of the rockies, located just south of haleyville; cathedral caverns in marshall county, named for its cathedral-like appearance, features one of

the largest cave entrances and stalagmites in the world; ecor rouge in fairhope, the highest coastline point between maine and mexico; desoto caverns in childersburg, the first officially recorded cave in the united states; noccalula falls in gadsden features a 90-foot waterfall; dismals canyon near phil campbell, home to two waterfalls, six natural bridges and allegedly served as a hideout for legendary outlaw jesse james; stephens gap cave in jackson county boasts a 143-foot pit, two waterfalls and is one of the most photographed wild cave scenes in america; little river canyon near fort payne, one of the nation's longest mountaintop rivers; rickwood caverns near warrior features an underground pool, blind cave fish and 260-million-year-old limestone formations; and the walls of jericho canyon on the alabama-tennessee

state line. a -wide meteorite impact crater is located in elmore county, just north of montgomery. this is the wetumpka crater, the site of "alabama's greatest natural disaster". a -wide meteorite hit the area about 80 million years ago. the hills just east of downtown wetumpka showcase the eroded remains of the impact crater that was blasted into the bedrock, with the area labeled the wetumpka crater or astrobleme ("star-wound") because of the concentric rings of fractures and zones of shattered rock that can be found beneath the surface. in 2002, christian koeberl with the institute of geochemistry university of vienna published evidence and established the site as the 157th recognized impact crater on earth. climate the state is classified as humid subtropical (cfa) under the koppen climate classification.

the average annual temperature is 64f (18c). temperatures tend to be warmer in the southern part of the state with its proximity to the gulf of mexico, while the northern parts of the state, especially in the appalachian mountains in the northeast, tend to be slightly cooler. generally, alabama has very hot summers and mild winters with copious precipitation throughout the year. alabama receives an average of of rainfall annually and enjoys a lengthy growing season of up to 300 days in the southern part of the state. summers in alabama are among the hottest in the u.s., with high temperatures averaging over throughout the summer in some parts of the state. alabama is also prone to tropical storms and hurricanes. areas of the state far away from the gulf are not immune to the effects of the storms, which often

dump tremendous amounts of rain as they move inland and weaken. south alabama reports many thunderstorms. the gulf coast, around mobile bay, averages between 70 and 80 days per year with thunder reported. this activity decreases somewhat further north in the state, but even the far north of the state reports thunder on about 60 days per year. occasionally, thunderstorms are severe with frequent lightning and large hail; the central and northern parts of the state are most vulnerable to this type of storm. alabama ranks ninth in the number of deaths from lightning and tenth in the number of deaths from lightning strikes per capita. alabama, along with oklahoma and iowa, has the most confirmed f5 and ef5 tornadoes of any state, according to statistics from the national climatic data center for the period january

1, 1950, to june 2013. several long-tracked f5/ef5 tornadoes have contributed to alabama reporting more tornado fatalities since 1950 than any other state. the state was affected by the 1974 super outbreak and was devastated tremendously by the 2011 super outbreak. the 2011 super outbreak produced a record amount of tornadoes in the state. the tally reached 62. the peak season for tornadoes varies from the northern to southern parts of the state. alabama is one of the few places in the world that has a secondary tornado season in november and december besides the typically severe spring. the northern partalong the tennessee river valleyis most vulnerable. the area of alabama and mississippi most affected by tornadoes is sometimes referred to as dixie alley, as distinct from the tornado alley of the southern

plains. winters are generally mild in alabama, as they are throughout most of the southeastern united states, with average january low temperatures around in mobile and around in birmingham. although snow is a rare event in much of alabama, areas of the state north of montgomery may receive a dusting of snow a few times every winter, with an occasional moderately heavy snowfall every few years. historic snowfall events include new year's eve 1963 snowstorm and the 1993 storm of the century. the annual average snowfall for the birmingham area is per year. in the southern gulf coast, snowfall is less frequent, sometimes going several years without any snowfall. alabama's highest temperature of was recorded on september 5, 1925, in the unincorporated community of centerville. the record low of occurred on january

30, 1966, in new market. flora and fauna alabama is home to a diverse array of flora and fauna in habitats that range from the tennessee valley, appalachian plateau, and ridge-and-valley appalachians of the north to the piedmont, canebrake, and black belt of the central region to the gulf coastal plain and beaches along the gulf of mexico in the south. the state is usually ranked among the top in nation for its range of overall biodiversity. alabama is in the subtropical coniferous forest biome and once boasted huge expanses of pine forest, which still form the largest proportion of forests in the state. it currently ranks fifth in the nation for the diversity of its flora. it is home to nearly 4,000 pteridophyte and spermatophyte plant species. indigenous animal species in the state include 62 mammal species,

93 reptile species, 73 amphibian species, roughly 307 native freshwater fish species, and 420 bird species that spend at least part of their year within the state. invertebrates include 97 crayfish species and 383 mollusk species. 113 of these mollusk species have never been collected outside the state. census-designated and metropolitan areas cities demographics according to the 2020 united states census the population of alabama was 5,024,279 on april 1, 2020, which represents an increase of 244,543 or 5.12%, since the 2010 census. this includes a natural increase since the last census of 121,054 (502,457 births minus 381,403 deaths) and an increase due to net migration of 104,991 into the state. immigration from outside the u.s. resulted in a net increase of 31,180 people, and migration within the country

produced a net gain of 73,811 people. the state had 108,000 foreign-born (2.4% of the state population), of which an estimated 22.2% were undocumented (24,000). the center of population of alabama is located in chilton county, outside the town of jemison. ancestry those citing "american" ancestry in alabama are of overwhelmingly english extraction, however most english americans identify simply as having american ancestry because their roots have been in north america for so long, in many cases since the early sixteen hundreds. demographers estimate that a minimum of 2023% of people in alabama are of predominantly english ancestry and state that the figure is probably much higher. in the 1980 census 1,139,976 people in alabama cited that they were of english ancestry out of a total state population of 2,824,719

making them 41% of the state at the time and the largest ethnic group. in 2011, 46.6% of alabama's population younger than age1 were minorities. the largest reported ancestry groups in alabama are american (13.4%), irish (10.5%), english (10.2%), german (7.9%), and scots-irish (2.5%) based on 2006-2008 census data. the scots-irish were the largest non-english immigrant group from the british isles before the american revolution, and many settled in the south, later moving into the deep south as it was developed. in 1984, under the davisstrong act, the state legislature established the alabama indian affairs commission. native american groups within the state had increasingly been demanding recognition as ethnic groups and seeking an end to discrimination. given the long history of slavery and associated racial

segregation, the native american peoples, who have sometimes been of mixed race, have insisted on having their cultural identification respected. in the past, their self-identification was often overlooked as the state tried to impose a binary breakdown of society into white and black. the state has officially recognized nine american indian tribes in the state, descended mostly from the five civilized tribes of the american southeast. these are the following. poarch band of creek indians (who also have federal recognition) mowa band of choctaw indians star clan of muscogee creeks echota cherokee tribe of alabama cherokee tribe of northeast alabama cher-o-creek intra tribal indians ma-chis lower creek indian tribe piqua shawnee tribe ani-yun-wiya nation the state government has promoted recognition

of native american contributions to the state, including the designation in 2000 for columbus day to be jointly celebrated as american indian heritage day. language most alabama residents (95.1% of those five and older) spoke only english at home in 2010, a minor decrease from 96.1% in 2000. alabama english is predominantly southern, and is related to south midland speech which was taken across the border from tennessee. in the major southern speech region, there is the decreasing loss of the final r, for example the "boyd" pronunciation of "bird". in the northern third of the state, there is a south midland "arm" and "barb" rhyming with "form" and "orb". unique words in alabama english include: redworm (earthworm), peckerwood (woodpecker), snake doctor and snake feeder (dragonfly), tow sack (burlap bag), plum

peach (clingstone), french harp (harmonica), and dog irons (andirons). religion in the 2008 american religious identification survey, 86% of alabama respondents reported their religion as christian, including 6% catholic, with 11% as having no religion. the composition of other traditions is 0.5% mormon, 0.5% jewish, 0.5% muslim, 0.5% buddhist, and 0.5% hindu. alabama is located in the middle of the bible belt, a region of numerous protestant christians. alabama has been identified as one of the most religious states in the united states, with about 58% of the population attending church regularly. a majority of people in the state identify as evangelical protestant. , the three largest denominational groups in alabama are the southern baptist convention, the united methodist church, and non-denominational

evangelical protestant. in alabama, the southern baptist convention has the highest number of adherents with 1,380,121; this is followed by the united methodist church with 327,734 adherents, non-denominational evangelical protestant with 220,938 adherents, and the catholic church with 150,647 adherents. many baptist and methodist congregations became established in the great awakening of the early 19th century, when preachers proselytized across the south. the assemblies of god had almost 60,000 members, the churches of christ had nearly 120,000 members. the presbyterian churches, strongly associated with scots-irish immigrants of the 18th century and their descendants, had a combined membership around 75,000 (pca28,009 members in 108 congregations, pc(usa)26,247 members in 147 congregations, the cumberland

presbyterian church6,000 members in 59 congregations, the cumberland presbyterian church in america5,000 members and fifty congregations plus the epc and associate reformed presbyterians with 230 members and nine congregations). in a 2007 survey, nearly 70% of respondents could name all four of the christian gospels. of those who indicated a religious preference, 59% said they possessed a "full understanding" of their faith and needed no further learning. in a 2007 poll, 92% of alabamians reported having at least some confidence in churches in the state. although in much smaller numbers, many other religious faiths are represented in the state as well, including judaism, islam, hinduism, buddhism, sikhism, the bahai faith, and unitarian universalism. jews have been present in what is now alabama since 1763,

during the colonial era of mobile, when sephardic jews immigrated from london. the oldest jewish congregation in the state is congregation sha'arai shomayim in mobile. it was formally recognized by the state legislature on january 25, 1844. later immigrants in the nineteenth and twentieth centuries tended to be ashkenazi jews from eastern europe. jewish denominations in the state include two orthodox, four conservative, ten reform, and one humanistic synagogue. muslims have been increasing in alabama, with 31 mosques built by 2011, many by african-american converts. several hindu temples and cultural centers in the state have been founded by indian immigrants and their descendants, the best-known being the shri swaminarayan mandir in birmingham, the hindu temple and cultural center of birmingham in pelham,

the hindu cultural center of north alabama in capshaw, and the hindu mandir and cultural center in tuscaloosa. there are six dharma centers and organizations for theravada buddhists. most monastic buddhist temples are concentrated in southern mobile county, near bayou la batre. this area has attracted an influx of refugees from cambodia, laos, and vietnam during the 1970s and thereafter. the four temples within a ten-mile radius of bayou la batre, include chua chanh giac, wat buddharaksa, and wat lao phoutthavihan. the first community of adherents of the bahai faith in alabama was founded in 1896 by paul k. dealy, who moved from chicago to fairhope. bahai centers in alabama exist in birmingham, huntsville, and florence. health in 2018, life expectancy in alabama was 75.1 years, below the national average of

78.7 years and is the third lowest life expectancy in the country. factors that can cause lower life expectancy are maternal mortality, suicide, and gun crimes. a centers for disease control and prevention study in 2008 showed that obesity in alabama is a problem, with most counties having more than 29% of adults obese, except for ten which had a rate between 26% and 29%. residents of the state, along with those in five other states, were least likely in the nation to be physically active during leisure time. alabama, and the southeastern u.s. in general, has one of the highest incidences of adult onset diabetes in the country, exceeding 10% of adults. on may 14, 2019, alabama passed the human life protection act, banning abortion at any stage of pregnancy unless there is a "serious health risk", with no exceptions