Latitude, Equator, Arctic; Antarctic, Tropic of Cancer & Capricorn - Latitude 34 North - Cities; Latitude Pole star Latitude Latitude indicates the location of a place on Earth north or south of the Equator . Latitude is an angular measurement in degrees (marked with °) ranging from 0° at the Equator to 90° at the poles (90° N for the North Pole or 90° S for the South Pole ). Degrees of latitude are parallel so the distance between each degree remains almost constant. Each degree of latitude is approximately 69 miles (111 kilometers ) apart. The distance varies (due to the earth's slightly ellipsoid shape) from 68.703 miles (110.567 km) at the equator to 69.407 (111.699 km) at the poles. This is convenient because each minute of latitude (1/60th of a degree) is approximately one mile .

Page Index The South Frigid Zone , south of the Antarctic Circle The Tropics The tropics are the geographic region of the Earth centered on the equator and limited in latitude by the Tropic of Cancer in the northern hemisphere , at approximately 23° 26' (23.5°) N latitude, and the Tropic of Capricorn in the southern hemisphere at 23° 26' (23.5°) S. This area includes all the parts of the Earth where the sun reaches a point directly overhead at least once during the solar year . Tropical plants and animals are those species native to the tropics. Tropical is also sometimes used in a general sense for a tropical climate, a climate that is warm to hot and moist year-round, often with the sense of lush vegetation. However, there are places in the tropics that are anything but "tropical" in this sense, with even alpine tundra and snow-capped peaks, including Mauna Kea, Mt. Kilimanjaro, and the Andes as far south as the northernmost parts of Chile and Argentina.

Places in the tropics which are drier with low humidity but extreme heat are the Sahara Desert, Central Africa, and Northern Australian Outback. The temperate zone The north temperate zone extends from the Tropic of Cancer at about 23.5 degrees north latitude to the Arctic Circle at about 66.5 degrees north latitude. The south temperate zone extends from the Tropic of Capricorn at about 23.5 degrees south latitude to the Antarctic Circle at about 66.5 degrees south latitude. These regions experience four seasons, spring, summer, autumn and winter. Within these borders there are many individual climate types, which are generally grouped into two categories; continental and maritime , or Oceanic climate. The difference in these regions between summer and winter are generally subtle, warm or cool (relatively speaking), rather than extreme, burning hot or freezing cold. However, a temperate climate can have very unpredictable weather and violent storms especially in spring and summer. The weather pattern can change rapidly; one day it may be sunny, the next it may be raining, and after that it may be cloudy. These erratic weather patterns occur in summer as well as winter. Polar climate There are two distinct types of polar climate .

The tundra climate is the less severe of the two, and there is at least one month that has an average temperature of above freezing . The second type of polar climate is known by various names including the "ice cap climate" and the "perpetual frost climate" and features sub-freezing average temperatures year-round. Return to the page index. Return to the top of the page. The Tilted Earth The planet Earth has an axial tilt of about 23° 27´ in relation to the sun . The northern end of the Earth's axis always points to the same place in space (towards the star called Polaris or the North Star). Because the axis is tilted in the same direction all year as the Earth orbits the Sun, the number of hours of daylight and the angle at which the sun light strikes the earth changes. This is what causes the seasons in the temperate zones . The hemisphere (half part of earth) tilted away from the Sun experiences winter while the hemisphere tilted towards the Sun will experience summer (see effect of sun angle on climate ).

The hemisphere that is currently tilted toward the Sun experiences more hours of sunlight each day, and the sunlight at midday also strikes the ground at an angle nearer the vertical and thus delivers more heat . From Wikipedia: In astronomy , axial tilt is the inclination angle of a planet's rotational axis in relation to a perpendicular to its orbital plane . It is also called axial inclination or obliquity . The axial tilt is expressed as the angle made by the planet's axis and a line drawn through the planet's center perpendicular to the orbital plane . The sun "travels " between the Tropic of Cancer (23.5 N) on the Northern Solstice (first day of summer in the Northern Hemisphere) to the Tropic of Capricorn (23.5 S) on the Southern Solstice and back to the Tropic of Cancer in one year (365 days). Thus the sun travels 47 degrees of latitude * 2 (to compensate for the round trip) = 94 degrees of latitude during a solar year . It is a simple calculation to compute the average daily movement of the sun (94 degrees/365 days = ~.258 degrees/day or ~15.5 nautical miles /day.

Axis Tilt and Solar Altitude The annual change in the relative position of the Earth´s axis in relationship to the sun causes the height of the sun ( solar elevation angle ) to vary in our skies. The difference in maximum solar altitude for any location on the Earth over a one year period is 47° (2 x 23.5° = 47°). For example, at 34° N maximum height of the sun varies from 79.6° on the summer solstice to 32.6° N on the winter solstice. Vanuatu – Tropical Plants -Garden Study Tour -Learn Gardening at home Plant Directory Vanuatu – Tropical Plants Many of our most magnificent gardens can be found in hot places. The range of plants available for such situations, provide a palette of unique textures, colours and shapes. The heat, and humidity in moister areas, encourages diversity of plant life. With the right approach, and careful selection of plants, a hot place can be turned into a very livable garden. Heliconia What causes an area to be warm? There are a number of things which contribute to a garden space becoming hot. Most heat will come directly from the sun.

Generally the closer an area is to the equator the warmer it is. The average maximum daily temperature will generally increase the further you move away from coastal areas. The sea or ocean has a temperature moderating effect. Temperature also decreases as altitude increases, so even in tropical regions high altitude sites will normally be significantly cooler than adjacent lowland sites. Some coastal areas may also remain warmer than other areas at the same latitude (distance from the equator) due to the presence of warm ocean currents. Cloud cover has an effect on air temperature near the earth's surface, by keeping it cooler in the day, but warmer at night as warmth cannot escape the atmosphere. Crinum Tropics Tropical areas are those parts of the world that fall between the Tropics of Cancer and Capricorn, which are lines of latitude lying 23.5 degrees north and south, respectively, of the equator. The most highly populated parts of these areas are typically hot and humid most of the year, with a mainly dry period during the winter and a pronounced wet season during the summer period. Humidity becomes even higher during the rainy season. Many of these areas may also be subject to cyclones and severe storms.

Vanuatu lies between 13o south of the equator and 23o south of the equator. Sub-tropics Generally warm like the tropics, but conditions may be more seasonal. Temperature fluctuations may be greater than for tropical areas. Sub-tropical areas can suffer from frosts, particularly inland areas. They can also have very hot days. Subtropical climates can be generally described as areas outside the tropics which exhibit a few features similar to those found in the tropics. Areas outside the tropics can be described as zones south of the Tropic of Capricorn, and zones north of the Tropic of Cancer. Acalypha godseffiana variety Greenhouses A greenhouse is simply a structure or building used to provide suitable growing conditions for particular plants that could not normally be grown, or could only be grown with difficulty, in the outside environment. Tropical plants are most commonly grown as greenhouse or indoor plants in cooler climates. Zingiber spectabile Poleshifts (1) POLESHIFTS 1. The tilt of the axis The rhythms of life on earth are largely regulated by the two fundamental motions of our planet: its daily rotation on its axis and its annual revolution around the sun.

The earth rotates once every 23 hours 56 minutes and 4 seconds – the earth-day. Since the earth rotates on its axis from west to east, or anticlockwise as viewed from above the north pole, the sun appears to rise in the east and set in the west. The earth revolves around the sun from west to east (anticlockwise) about once every 365.25 days – the earth-year. As a spinning sphere (or rather oblate spheroid), the earth possesses a rotation axis, whose two ends mark the north and south geographic poles, with the equator being situated midway between them. If the earth stood perfectly upright on its axis – i.e. if its axis formed an angle of 90° with the plane of its orbit around the sun (the ecliptic) – the equator would lie in the plane of the ecliptic. The sun would then always shine above the equator, and all regions of the earth between the two poles would enjoy a constant alternation of 12 hours’ daylight and 12 hours’ darkness. The earth’s axis, however, is not perpendicular to the ecliptic.

At present the equator is tilted at an angle of about 23.4° in relation to the ecliptic, and the earth’s axis makes an angle of 23.4° with a line drawn perpendicular to the ecliptic; in other words, the obliquity of the ecliptic is 23.4°. The tilt of the earth’s axis gives rise to two important parallels of latitude in each hemisphere: the tropics and the polar circles: the tropics of Cancer and Capricorn currently lie 23.4° north and south of the equator respectively, and the arctic and antarctic circles lie at 66.6° north and south latitude respectively (i.e. 23.4° from the north and south poles). These boundaries divide the earth’s surface into three distinct zones: the tropical or torrid zone (the region between the two tropics); the temperate zones (the region in each hemisphere between the tropics and the polar circles); and the frigid or polar zones (the region in each hemisphere inside the polar circles).

The polar zones do not enjoy a regular alternation of day and night throughout the year; the sun is below the horizon for between one day (at the polar circles) and six months (at the poles) each year. In the tropical zone the sun is vertically overhead sometime each year, whereas in the temperate and polar zones, the sun is always at some angle less than 90°. Fig. 1. The tilt of the earth’s axis. The existence of the four seasons is due mainly to the earth’s tilt and, to a lesser extent, to the ellipticity of the earth’s orbit (i.e. the extent to which it departs from a perfect circle). If the earth’s axis stood upright, there would therefore be no distinct seasons. To describe the positions and motions of astronomical objects, they are considered to lie on an imaginary sphere surrounding the earth, known as the celestial sphere. The north and south celestial poles are the projection onto the celestial sphere of the earth’s north and south geographic poles, and the celestial equator is the projection of the earth’s equator. The north and south poles of the ecliptic are the projection of a line perpendicular to the ecliptic.

It does not matter whether this line is projected into space from the earth or from the sun, since the celestial sphere is conceived as being so far away that the ecliptic pole will fall on a unique point. The north and south celestial poles are 23.4° from the north and south ecliptic poles respectively. If the earth’s axis was upright instead of tilted, the celestial poles would coincide with the ecliptic poles. The north ecliptic pole lies in the constellation Draco, while the north celestial pole lies very close to Alpha Ursae Minoris, the current polestar. Fig. 2. The celestial sphere. 2.

The four seasons The inclination of the earth’s axis gives rise to four important points in the earth’s orbit, which mark the beginning and end of the four seasons: at the vernal (or spring) equinox, the sun is above the equator; it then appears to move northwards and rises higher and higher in the sky (in the northern hemisphere) until the summer solstice, when it is above the tropic of Cancer; it then appears to move back towards the equator until the autumnal equinox, when it is again above the equator; finally it proceeds southwards until the winter solstice, when it is above the tropic of Capricorn. In reality, of course, it is the earth that revolves around the sun, not the sun around the earth. In the northern hemisphere, the vernal equinox falls on 20 March, the summer solstice on 20/21 June, the autumn equinox on 22/23 September, and the winter solstice on 21/22 December. In the southern hemisphere spring and autumn, and summer and winter are reversed.

Although, astronomically, each season lasts three months, for non-astronomers it is more sensible over most of the northern hemisphere to think in terms of a four-month winter (December to March), a two-month spring (April/May), a fourth-month summer (June to September), and a two-month autumn (October/November). A lag of a month or more occurs between the time of maximum and minimum solar radiation and the warmest and coldest months, because the earth takes time to respond to changes in the amount of incoming solar energy. The two equinoctial points are the points (or nodes) where the ecliptic intersects the celestial equator. The equinoxes are therefore the two days of the year when the sun is directly above the earth’s equator. Equinox means ‘equal night’, and at the equinoxes day and night everywhere are about 12 hours long. Fig. 3. The four seasons.

At the summer solstice (in the northern hemisphere) the sun reaches its northernmost point and rises to its highest point in the sky, and therefore the day reaches its maximum length, while at the winter solstice, the sun reaches its southernmost point, appears at its lowest point in the sky, and therefore the night reaches its maximum length. The sun’s rays fall vertically on the equator at the equinoxes, and vertically on the tropic of Cancer and the tropic of Capricorn at the summer and winter solstices respectively. The tropics are therefore that region of the earth on which the sun’s rays fall vertically at some point of the year, while at all other places on the earth the sun’s rays arrive at an oblique angle, so that they receive less heat. At the equinoxes the sun’s declination is 0° as it is then traversing the celestial equator (declination is the number of degrees north or south of the celestial equator). It therefore rises and sets due east and due west all over the globe.

In the northern hemisphere, the sun rises to the north of east in the summer and to the south of east in winter, reaching its northernmost and southernmost positions at the summer and winter solstices respectively, when it has its greatest declination of 23.4° north or south. The distance from due east and west of the point on the horizon where the sun rises and sets depends not only on the time of year but also on the latitude in question – the higher the latitude the greater the distance. 1 The inclination of the earth’s axis means that different parts of the earth receive different amounts of solar radiation, and it is the main cause of the seasonal rhythms. A secondary factor is that the earth follows an elliptical orbit around the sun, so that its distance from the sun varies. At present the earth reaches perihelion – the point in its orbit closest to the sun (147 million km) – on 2-5 January, i.e. during winter in the northern hemisphere, and it reaches aphelion – the point in its orbit furthest from the sun (152 million km) – on 3-6 July, i.e. during summer in the northern hemisphere.

This means that the northern hemisphere has milder winters but cooler summers than the southern hemisphere, though the effect is moderated by the heat stored in the greater expanse of oceans in the southern hemisphere. The amount of solar radiation intercepted by the earth at perihelion is about 7% higher than at aphelion. Notes 1. The sun’s maximum annual deviation (Δ) north or south of the E-W line is given by the equation: sin Δ = sin ε / cos l where ε = obliquity of ecliptic, and l = latitude of observer. On the equator (lat. 0°) the total swing along the eastern horizon is therefore equal to twice the tilt of the earth’s axis. For any other latitude, it is greater. 3. Precession of the equinoxes The vernal and autumnal equinoxes occur at the two points in the earth’s orbit where the earth’s axis forms an exact right angle with a line joining the centre of the earth and sun, as viewed from directly above or below the earth.

The summer solstice occurs at the point in the earth’s orbit where its north pole is tilted directly towards the sun, and the winter solstice occurs at that point where it is tilted directly away from the sun. If the earth’s axis always pointed to exactly the same point in space, the vernal equinox would occur at the same point in the earth’s orbit every year, and the earth would move through a full circle of 360° between successive equinoxes. However the earth’s axis gyrates very slowly clockwise (viewed from above the north pole), describing a conical movement round the vertical, rather like the axis of a spinning top, and traces a complete circle among the stars about once every 26,000 years. According to modern science, this is caused by the gravitational pull of the moon and sun and, to a lesser extent, the planets on the earth’s slight equatorial bulge. The result is that the vernal equinox occurs a fraction of a degree before the earth reaches the point in its orbit where the equinox occurred the year before. This phenomenon is known as the precession of the equinoxes (though it might just as well be called the precession of the solstices).

The vernal equinox precesses at an average rate of about 50 arc-seconds (1/72°) per year, and it therefore occurs about twenty minutes earlier every year. This means that the earth does not revolve through 360° between two successive vernal equinoxes but only 359 71/72 degrees (or 359 degrees, 59 minutes and 10 seconds). The actual rate of precession fluctuates around the average figure of 50". The annual rate of precession for the year 2000 (epoch J2000.0) is 50.288". Fig. 4. The long-term wobble, or precession, of the earth’s axis. The sidereal year is the time the earth takes to make one 360° revolution around the sun, measured between two successive conjunctions of a particular star, and is currently equal to 365.256363 days.

The tropical year (also called the solar or equinoctial year) is the time the earth takes to make one revolution around the sun, measured between two successive vernal equinoxes, and is currently equal to 365.242190 days. In other words, at present the tropical year is about 20.4 minutes shorter than the sidereal year. The zodiac is a zone or belt of the celestial sphere, extending about 8 degrees on either side of the ecliptic, and divided into twelve portions or constellations. During each annual revolution around the sun, the earth passes through each constellation of the zodiac from west to east, at the rate of approximately one degree per day. At the moment of the vernal equinox, a line from the centre of the earth through the sun and extended outwards will cross the circle of the zodiac at the equinoctial point – one of the two points where the celestial equator intersects the ecliptic.

Since each successive vernal equinox occurs when the earth is slightly to the west of its orbital position at the last vernal equinox, the vernal equinoctial point advances slowly westward, so that from equinox to equinox the earth moves ‘backwards’ through the constellations of the zodiac (i.e. in the opposite direction to that in which it orbits the sun). At an average rate of precession of 50 arc-seconds a year, the sun enters a new constellation (covering an average of 30 degrees of arc) every 2160 years (a period known in theosophy as the messianic cycle), and takes 25,920 years to complete a full circuit of the zodiac. 1 A precessional cycle is also known as the Great Year or Platonic Year. There is an important distinction between the constellations (or houses) of the zodiac and the signs of the zodiac. 2 The constellations are groups of stars encircling the earth at a distance of many light-years.

They are sometimes said to be ‘fixed’, though every star actually has its own proper motion, so that over long periods of time the stars of a constellation alter their position in relation to one another. The signs of the zodiac, on the other hand, are regions of space permeating and surrounding the earth. The vernal equinoctial point is the point on the celestial equator which the sun crosses at the vernal equinox, and the corresponding point on the earth’s equator is defined as the beginning of the sign Aries – whatever the constellation in which this occurs. As the vernal equinoctial point gradually shifts around the celestial equator during a precessional cycle, the signs shift around the earth’s equator accordingly. The signs are therefore not fixed, while the constellations (relatively speaking) are. Since Aries is traditionally regarded as the first sign and constellation of the zodiac, a precessional cycle could be said to begin when the first point of the sign of Aries coincides with the first point of the constellation Aries (i.e. when the earth, the sun, and the first point of the constellation Aries are in a straight line at the moment of the vernal equinox).

This does not occur at the beginning of the Age of Aries, but at the end, for the following reason. Since the earth revolves around the sun from west to east, the westernmost point of each constellation (each assumed to cover 30° of arc) is counted as 0° of that constellation (and 30° of the preceding constellation); the first point of Aries (0° Aries) is therefore also 30° Pisces. However, the equinoctial point precesses in the opposite direction – from east to west. Thus when, in the course of precession, the sun leaves the constellation Taurus and enters Aries, it enters the 30th degree of Aries, and does not coincide with the first point of the constellation Aries until the end of the Age of Aries. According to H.P. Blavatsky, the Age of Taurus ended and the Age of Aries began in 2410 BCE, the Piscean Age began in 255 BCE, and the Aquarian Age began at the end of the 19th century. These dates assume that each constellation spans 30°.

It will be many centuries before the equinoctial point enters the actual constellation of Aquarius. 3 Fig. 5. The precession of the equinoxes. Position A shows the first point of the sign Aries coinciding with the first point of the constellation Aries. A quarter of a precessional cycle later (6480 years), it coincides with the first point of Capricorn (position B), then Libra (position C), and Cancer (position D). After a total of 25,920 years, the earth returns to position A. 4 Notes 1. H.P. Blavatsky gives the length of the precessional cycle as 25,868 years, equivalent to 50.10 arc-seconds per year (H.P. Blavatsky, The Secret Doctrine, Theos. Univ. Press (TUP), 1977 (1888), 2:330fn). However, she also says that 25,920 years is the ‘exact period of revolution of the heavens’ (H.P. Blavatsky Collected Writings, Theos. Publ.

House, 1950-91, 14:360). In 945 BCE (before Christian era) the Hindus calculated the rate of precession to be 48.57 arc-seconds per year (see The Theosophist, Sept. 1881, p. 263). On the basis of the current rate of increase in precession (0.0002 arc-seconds a year), the annual rate of precession would have been 50.10" around 1060 CE, and 49.699" in 945 BCE. Blavatsky sometimes refers to the precessional cycle as the ‘sidereal year’ or ‘tropical year’. Nowadays these terms have different meanings, as noted above in the text. 2. G. de Purucker, Fountain-Source of Occultism, TUP, 1974, pp. 125, 139-42. 3. Blavatsky Collected Writings, 8:174. See Appendix 1: The zodiac and precession. 4.

Fountain-Source of Occultism, p. 672. 4. The changing polestar The north and south celestial poles are the points on the celestial sphere directly above and below the earth’s north and south geographic poles respectively. The north and south ecliptic poles are the points directly above and below a line drawn perpendicular to the ecliptic. The celestial poles are often situated in wide open space, but at other times they come close to, and occasionally coincide with, a star, which is then called the polestar. In the northern hemisphere, the present polestar (Polaris) is the star at the end of Ursa Minor’s tail. In the southern hemisphere, there is currently no bright star near the celestial pole; the southern polestar, Sigma Octantis, is only of the 5th magnitude, whereas Polaris is of the 2nd magnitude. An observer on the earth’s surface sees only half the celestial sphere at any one time. The visible half is bounded by the observer’s horizon, a plane that cuts the celestial sphere 90° from the observer’s zenith (the point on the celestial sphere directly above him or her).

As seen from the equator, true polestars lie on the horizon while all other stars rise at right angles to the horizon, remaining above it for 12 hours. As viewed from either of the poles, a polestar remains stationary overhead while all other stars move in circles parallel to the horizon, remaining permanently above it. At intermediate latitudes, the apparent motion of the stars lies between these two extremes: some stars rise and set, but others circle around the poles without setting and are known as circumpolar stars. At a latitude of 25°N, for example, the north celestial pole lies 25° above the north horizon and therefore all stars within 25° of the celestial pole are circumpolar, while all other stars visible from that latitude rise and set. Since the earth rotates in an anticlockwise direction, the stars appear to revolve around the celestial poles in a clockwise direction, completing one revolution every day. The gyration of the earth’s axis that produces the precession of the equinoxes involves a slow change in the direction in which the axis points in space (the tilt, according to modern astronomy, remaining more or less the same).

The axis slowly sweeps an approximate circle, with a radius of about 23.5° around the poles of the ecliptic in the course of a precessional cycle. Since the polestar is simply the star closest to the celestial poles at any given time, a series of different stars take on the role of polestar during a precessional cycle. Alpha Draconis (Thuban) was closest to the north celestial pole around 2700 BCE. The north celestial pole currently points to within 1° of Polaris, and will point closest to it in 2100. In 12,000 years the star closest to the north celestial pole will be Vega, the brightest star in the Lyre. According to modern science, the tilt of the earth’s axis does not remain exactly the same but gradually varies within very narrow limits owing to gravitational perturbations caused by the sun, moon and planets (especially Jupiter, Mars, and Venus). It has been established by observation that the tilt is steadily decreasing by around 0.47 arc-seconds a year (about a hundredth of a degree per century).

On 1 January 1950 the obliquity was 23°26'45", and on 1 January 2000 it was 23°26'21". On the basis of calculations of gravitational perturbations, scientists theorize that the tilt oscillates between about 22.1° and 24.5° over a period of about 41,000 years. 1 The slight variation in the tilt of the earth’s axis means that the curve described by the earth’s north pole around the north ecliptic pole is not a perfect circle. 2 According to theosophy, 3 on the other hand, the axis gradually inverts through a full 360 degrees, at an average rate of 4 degrees per precessional cycle (0.56 arc-seconds per year), and therefore traces not a circle but a spiral around the poles of the ecliptic. In addition, sudden axial disturbances occur from time to time, resulting in major cataclysms. 4 Scientists would dismiss the idea of a gradual inversion of the poles as impossible because they do not know of any force that could produce such an effect.

Then again, they cannot explain what causes the earth to rotate on its axis – but it keeps on turning just the same! Fig. 6. The changing polestar. Theosophy postulates that the earth’s axis does not trace a circle around the ecliptic pole but a spiral. Notes 1. A. Berger & M.F. Loutre, ‘Insolation values for the climate of the last 10 million years’, Quaternary Science Reviews, vol. 10, 1991, pp. 297-317. 2. Furthermore, the ‘circle’ is not smooth but wavy owing to the phenomenon of nutation, a ‘nodding’ movement of the earth’s axis with a period of 18.6 years and an amplitude of 9.2 arc-seconds. Its chief cause lies in the fact that the moon’s orbital plane is inclined at about 5° to the earth’s orbital plane and precesses around it in 18.6 years (‘ideal’ figure: 18 years). The ‘circle’ described in a complete precessional cycle therefore has about 1440 waves (= 25,920/18).

(It is interesting to note that there are 1440 minutes in a day, and a human being breathes an average of 18 times a minute: 18 x 1440 = 25,920.) The approximate circle (with superimposed nutation) is traced in an anticlockwise direction as viewed from the earth, or in a clockwise direction as viewed from the north ecliptic pole. 3. H.P. Blavatsky, The Secret Doctrine, TUP, 1977 (1888), 2:331, 357, 407-8, 768; G. de Purucker, Fountain-Source of Occultism, TUP, 1974, pp. 346-7; Samson Arnold Mackey, Mythological Astronomy of the Ancients Demonstrated (1822/23), Wizards Bookshelf, 1973. 4. The Secret Doctrine, 1:369, 2:144-5, 274, 314, 330, 350; W.Q.

Judge, The Ocean of Theosophy, TUP, 1973 (1893), pp. 135-6, 140. What lines make up the earth's grid system? | Reference.com What lines make up the earth's grid system? A: Quick Answer The most common grid system used to map the earth consists of latitude and longitude lines. Line zero for latitude is known as the equator, and it divides the northern and southern hemispheres. Line zero for longitude is the prime meridian, which runs though Greenwich, England. Full Answer Other significant markers of the grid system include the international date line, which is the exact opposite of the prime meridian, and the Tropics of Cancer and Capricorn, each at 23.5 degrees north and south of the equator, respectively. The seasons change very little in the tropics, unlike at the more extreme ends of latitude, where seasonal change is much more prominent. What is the latitude of the equator? | Reference.com What is the latitude of the equator? A: Quick Answer The equator is located at 0 degrees latitude.

Because the Earth is widest at the equator, it is the longest line of latitude at 24,901.55 miles. Lines of latitude are imaginary lines that measure degrees north and south of the equator. Full Answer The equator divides the Earth into northern and southern hemispheres. Other important lines of latitude are the Tropic of Cancer and the Tropic of Capricorn, at 23.5 degrees north and south latitude respectively. The area in between these two lines of latitude is known as the tropics. The North Pole is located at 90 degrees north latitude, and the South Pole is situated at 90 degrees south latitude. Lattitude | Article about Lattitude by The Free Dictionary Lattitude | Article about Lattitude by The Free Dictionary Also found in: Dictionary , Thesaurus , Medical , Legal , Wikipedia . latitude, angular distance of any point on the surface of the earth north or south of the equator. The equator is latitude 0°, and the North Pole and South Pole are latitudes 90°N and 90°S, respectively.

The length of one degree of latitude averages about 69 mi (110 km); it increases slightly from the equator to the poles as a result of the earth's polar flattening. Latitude is commonly determined by means of a sextant sextant, instrument for measuring the altitude of the sun or another celestial body; such measurements can then be used to determine the observer's geographical position or for other navigational, surveying, or astronomical applications. ..... Click the link for more information. or other instrument that measures the angle between the horizon and the sun or another celestial body, such as the North Star (see Polaris Polaris or North Star, star nearest the north celestial pole (see equatorial coordinate system). It is in the constellation Ursa Minor (see Ursa Major and Ursa Minor; Bayer designation Alpha Ursae Minoris) and marks the end of the handle of the Little Dipper. ..... Click the link for more information. ). The latitude is then found by means of tables that give the position of the sun and other bodies for that date and hour. An imaginary line on the earth's surface connecting all points equidistant from the equator (and thus at the same latitude) is called a parallel of latitude.

On most globes and maps parallels are usually shown in multiples of 5°. Because of their special meanings, four fractional parallels are also shown. These are the Tropic of Cancer (23 1-2°N) and the Tropic of Capricorn (23 1-2°S), marking the farthest points north and south of the equator where the sun's rays fall vertically (see tropics tropics, also called tropical zone or torrid zone, all the land and water of the earth situated between the Tropic of Cancer at lat. 23 1-2°N and the Tropic of Capricorn at lat. 23 1-2°S. ..... Click the link for more information. ), and the Arctic Circle Arctic Circle, imaginary circle on the surface of the earth at 66 1-2°N latitude, i.e., 23 1-2° south of the North Pole. It marks the northernmost point at which the sun can be seen at the winter solstice (about Dec. ..... Click the link for more information.

(66 1-2°N) and the Antarctic Circle Antarctic Circle, imaginary circle on the surface of the earth at 66 1-2°S lat., i.e., 23 1-2° north of the South Pole. It marks the southernmost point at which the sun can be seen at the winter solstice (about June 22) and the northernmost point of the southern polar ..... Click the link for more information. (66 1-2°S), marking the farthest points north and south of the equator where the sun appears above the horizon each day of the year (see also midnight sun midnight sun, phenomenon in which the sun remains visible in the sky continuously for 24 hr or longer, occurring only in the polar regions. The midnight sun is due to the fact that the plane of the earth's equator is tilted about 23 1-2° to the plane of the ecliptic (the ..... Click the link for more information. ). Parallels of latitude and meridians of longitude longitude , angular distance on the earth's surface measured along any latitude line such as the equator east or west of the prime meridian.

A meridian of longitude is an imaginary line on the earth's surface from pole to pole; two opposite meridians form a great circle dividing ..... Click the link for more information. together form a grid by which any point on the earth's surface can be specified. The term latitude is also used in various celestial coordinate systems (see ecliptic coordinate system ecliptic coordinate system, an astronomical coordinate system in which the principal coordinate axis is the ecliptic, the apparent path of the sun through the heavens. The ecliptic poles are the two points at which a line perpendicular to the plane of the ecliptic through the ..... Click the link for more information. ). latitude Celestial Sphere THE CELESTIAL SPHERE We observe the sky as it looks, not as it is. You feel like you are on top of the Earth (the result of gravity drawing you toward the Earth's center). In the example, you are at a latitude (your location along an arc from the Earth's equator to the rotation pole, given by lower case Greek letter Phi) of 45°, halfway between the Earth's equator and the north pole.

The latitude of the north pole is 90°, that of the equator 0°. The Earth appears to lie at the center of a fictional celestial sphere. You pretend that you are inside the sphere at the center looking out around you. Above your head is your zenith, while directly below you is your nadir (both of which are points on the celestial sphere). In between is the great circle of the horizon, which is the circle on the celestial sphere cut by a plane tangent to the Earth at your feet. Everything in the sky above the horizon is visible, while everything below it is not. The celestial sphere is tipped relative to the observer in the same way as is the Earth. The extension of the Earth's rotation axis to the sky defines the North and South Celestial Poles (the NCP and SCP), while the extension of the Earth's equatorial plane defines the celestial equator. The NCP is in the constellation Ursa Minor (the Smaller Bear) close to the direction of the star Polaris , otherwise called the North Star. The SCP is in the modern constellation Octans , the Octant, in the general direction of the faint southern pole star Sigma Octantis (Polaris Australis).

The circle that runs through the zenith, nadir, NCP, and SCP is the celestial meridian. The intersection of the celestial meridian and the horizon define north (N) and south (S), while that between the equator and the horizon define east (E) and west (W). The intersection of the celestial meridian and the celestial equator (upper case Greek letter Sigma) is down from the zenith by an angle equal to the latitude. The Earth rotates about its poles from west to east (counterclockwise as viewed from above the north pole), which makes the sky seem to rotate in the other direction about the north and south celestial poles parallel to the celestial equator. The elevation above the horizon (the altitude) of the NCP always equals the observer's latitude. If you are in the southern hemisphere, the south celestial pole (the SCP) is above the horizon, the NCP below it. A star on the celestial sphere seems to go around the observer on a daily path (red circle). The perpendicular angle of a star north or south of the celestial equator is given by its declination, indicated by lower case Greek letter Delta.

When the star drops below the horizon, it sets, while when it comes up above the horizon it rises. A star on the celestial equator rises exactly east, sets exactly west. The greater the declination, the farther north of west the star both sets and rises. If far enough north (declination 90° - latitude), the star misses the horizon and is circumpolar, that is, always visible. If the declination is far enough south, the star does not get above the horizon and is always invisible. THE ECLIPTIC Though in truth the Earth orbits the Sun , we feel stationary, which makes the Sun appear to go around the Earth once a year in the counterclockwise direction (from west to east, counter to its daily motion across the sky) along a steady path called the ecliptic. Since there are 365 (actually 365.2422...) days in the year, and 360° in the circle, the Sun moves to the east at the slow pace of only a bit under a degree per day.

At the same time it is constantly moving (rather, appearing to move) from east to west as a result of the Earth's rotation, just at a pace slightly slower than the stars because of its simultaneous easterly drift. The perpendiculars to the ecliptic plane define the ecliptic poles. The North Ecliptic Pole (NEP) is in Draco , the South Ecliptic Pole (SEP) in Dorado . The Earth's axis is tilted relative to the perpendiculars to the ecliptic plane by an angle of 23.5° (actually closer to 23.4°). The tilt separates the celestial and ecliptic poles by the same angle, which causes the circle of the ecliptic to be tilted relative to the celestial equator again by the same angle, which as a result is called the obliquity of the ecliptic. As it moves along the ecliptic against the background stars, which are there even if you cannot see them against the blue sky , the Sun therefore appears also to move north and south of the celestial equator.

As the Sun traverses the ecliptic path, it appears to move against a band of 12 ancient constellations called the Zodiac, which are given in traditional order are shown below. The second line for each entry gives the average date on which the Sun enters the constellation according to the official boundaries established in 1930 by the International Astronomical Union. They depend somewhat on the proximity of a leap year. The modern boundary of Ophiuchus (the Serpent Bearer) is crossed by the ecliptic between Scorpius and Sagittarius, making it an unofficial thirteenth constellation of the Zodiac. It has no standing as part of the classical, traditional Zodiac, however. The Sun enters it November 30. SUN AND SEASONS Twice a year, the Sun crosses the equator, on or about March 20 at a point called the Vernal Equinox, and on September 23 at the Autumnal Equinox (the terms derived from a northern hemisphere perspective). On these dates, the Sun has a declination of 0°, rises exactly east, sets exactly west, is up for 12 hours and down for 12 hours, hence the term equinox.

The equinox passages respectively announce the beginning of northern- hemisphere spring and autumn (and southern hemisphere autumn and spring). (In actual fact, the risings, settings, and 12-hour durations cannot be exact, since the Sun is continuously moving along the ecliptic and is on the equinoxes but for the moment. In addition, upward refraction by the Earth's atmosphere and the finite angular diameter of the Sun renders the equinox day a bit longer than 12 hours, night a bit shorter, all the while ignoring twilight.) As the Sun moves north of the equator from the Vernal Equinox, it rises and sets progressively more to the north of east and west. Days gradually become longer than 12 hours, nights shorter. On June 21, the Sun reaches its most northerly extent (as seen in the right-hand "Earth" in the illustration), at a declination of 23.5 degrees north at the Summer Solstice, to begin northern- hemisphere summer (southern hemisphere winter). It then rises as far north of east and sets as far north of west as possible. Northern hemisphere days are now the longest of the year, nights the shortest, the extent of the effect dependent on latitude.

Conversely, following the autumnal equinox, as the Sun moves south, it rises and sets progressively farther south of east and west. Northern hemisphere days now get shorter (less than 12 hours), nights longer (greater than 12 hours). On December 22, the Sun reaches its most southerly extent (see the left-hand "Earth"), at a declination of 23.5 degrees south, at the Winter Solstice to begin northern-hemisphere winter (southern hemisphere summer). It then rises as far south of east and sets as far south of west as possible. Northern-hemisphere daytime is now minimized, nighttime maximized. All the effects are reversed in the southern hemisphere, while at the Earth's equator, days and nights are always equal at 12 hours. When at the Summer Solstice, the northern-hemisphere Sun (north of the tropics) crosses the celestial meridian as high as possible, while at the Winter Solstice it crosses as far to south as possible.

In the summer, sunlight spreads itself over a smaller area of ground than it does in winter, and thereby heats the ground more efficiently, yielding more heat, so it is hot in the summer, cold in the winter. This effect is the sole cause of the Seasons . (The effect of the variation in distance between the Earth and the Sun caused by the Earth's elliptical orbit is of little consequence because of the power of the oceans to store heat.) Above the Arctic Circle at latitude 66.6° north (and below the Antarctic Circle, latitude 66.6° south), the Sun can be circumpolar in the summer, yielding 24 hours of sunlight and a midnight Sun ). The farther north of the Arctic Circle (or the farther south of the Antarctic Circle), the more days of midnight Sun you will see. In the tropics (between latitudes 23.5°N at the Tropic of Cancer and 23.5°S at the Tropic of Capricorn) the Sun can be overhead sometime during the year (on June 21 at the former, on December 22 at the latter).

TIME AND COORDINATES Your location on Earth is expressed through your latitude (your north-south position; see above) and longitude, which gives your east-west position. Draw a circle called a meridian from the north pole through your location to the south pole, then do the same through Greenwich, England to define the prime meridian, and note where they cross the equator. Your longitude (given by lower case Greek letter lambda) is the angle between the two intersections (of the meridians and the equator). In the illustration, the latitude of Greenwich is 51° 29' North (the longitude is by definition zero); those of Buenos Aries are 34° 35' South, 58° 29' West. There are 60 minutes (') in a degree of angle, 60 seconds (") in a minute. The angular displacement of a star to the west of the celestial meridian (as measured along the celestial equator, analogous to longitude) is called the hour angle, which is usually given in time units at a rate of 15° per hour.

Apparent solar time is given by the hour angle of the Sun plus 12 hours (the 12 hours added so that the "day" starts at midnight). Because of the eccentricity of the Earth's orbit and the obliquity of the ecliptic, apparent solar time does not keep a constant pace. Corrections for their effects lead to constant mean solar time, which can differ from apparent solar time by up to 17 minutes. The hour angle of the Sun, and therefore the time of day, varies continuously with longitude, wherein longitude differences exactly equal time differences. Standard times are the mean solar times of the closest standard meridians, which are displaced in units if 15° from Greenwich. (Political boundaries cause variances.) Star time, properly called sidereal time, is the hour angle of the Vernal Equinox. Because the Sun moves to the east along the ecliptic, the Sun takes longer to make a circuit of the sky on its daily path than does a star or the equinox, so the solar day is 4 minutes longer than the sidereal day.

As a result, the sidereal clock gains 4 minutes (actually 3 minutes 56 seconds) per day over the solar clock, starting from the time of solar passage across the autumnal equinox on September 23, when the two are the same. The right ascension of a star or any other celestial body (given by the lower-case Greek letter alpha) is the angle the body makes with the vernal equinox as measured to the east, again along the celestial equator. It too is usually measured in time units. The right ascension and hour angle of a body always add to equal the sidereal time. Given the sidereal time and the right ascension of a body, you can compute its hour angle, which with the declination allows you to set a telescope and to find anything in the sky. The equinoxes and solstices are set against the background of the ancient zodiacal constellations: EQUINOXES AND SOLSTICES Sagittarius *But see below. Because of rotation, the Earth bulges slightly at its equator (greatly exaggerated in the drawing to the left; the difference between the equatorial and polar diameters is only 40 kilometers).

The gravity of the Moon and Sun acting on the bulge causes the Earth's rotation axis to wobble around the perpendicular to its orbit with a period of 26,000 years, the phenomenon called precession. Precession causes the celestial poles (the NCP and the SCP) to move in circles around the ecliptic poles (the NEP and SEP), which changes the pole stars. In ancient Egyptian times, for example, the North Celestial Pole (NCP) pointed close to Thuban in Draco (the Dragon). Precession also causes the plane of the Earth's equator to wobble, which changes the directions of the equinoxes and solstices against the background stars (continuously altering the right ascensions and declinations of stars, though in a precisely known way). In ancient times, the Vernal Equinox was in Aries , which is why that constellation tops the classical list. In classical times the Summer and Winter Solstices were in Cancer and Capricornus , hence the names "Tropic of Cancer" and "Tropic of Capricorn." Our astronomical roots are deep indeed.

As a result of precession, around 1990 the Summer Solstice crossed the modern boundary from Gemini to Taurus, which now technically holds the point. Because the Summer Solstice is closer to the classic figure of Gemini than it is to that of Taurus, and since Gemini (along with Pisces, Libra, and Sagittarius) quarters the ecliptic, Gemini is still traditionally taken as the Solstice's celestial home. Figures are from STARS , James B. Kaler, Scientific American Library, Freeman, NY, copyright © James B. Kaler. To learn more about this subject, see The Ever-Changing Sky , James B. Kaler, Cambridge University Press, 2002. Copyright © James B. Kaler. All rights reserved. These contents are the property of the author and may not be reproduced in whole or in part without the author's express consent except in fair use for educational purposes. Thanks to reader number . Latitude | Article about latitude by The Free Dictionary Latitude | Article about latitude by The Free Dictionary Also found in: Dictionary , Thesaurus , Medical , Legal , Acronyms , Wikipedia .

latitude, angular distance of any point on the surface of the earth north or south of the equator. The equator is latitude 0°, and the North Pole and South Pole are latitudes 90°N and 90°S, respectively. The length of one degree of latitude averages about 69 mi (110 km); it increases slightly from the equator to the poles as a result of the earth's polar flattening. Latitude is commonly determined by means of a sextant sextant, instrument for measuring the altitude of the sun or another celestial body; such measurements can then be used to determine the observer's geographical position or for other navigational, surveying, or astronomical applications. ..... Click the link for more information. or other instrument that measures the angle between the horizon and the sun or another celestial body, such as the North Star (see Polaris Polaris or North Star, star nearest the north celestial pole (see equatorial coordinate system). It is in the constellation Ursa Minor (see Ursa Major and Ursa Minor; Bayer designation Alpha Ursae Minoris) and marks the end of the handle of the Little Dipper. ..... Click the link for more information. ).

The latitude is then found by means of tables that give the position of the sun and other bodies for that date and hour. An imaginary line on the earth's surface connecting all points equidistant from the equator (and thus at the same latitude) is called a parallel of latitude. On most globes and maps parallels are usually shown in multiples of 5°. Because of their special meanings, four fractional parallels are also shown. These are the Tropic of Cancer (23 1-2°N) and the Tropic of Capricorn (23 1-2°S), marking the farthest points north and south of the equator where the sun's rays fall vertically (see tropics tropics, also called tropical zone or torrid zone, all the land and water of the earth situated between the Tropic of Cancer at lat. 23 1-2°N and the Tropic of Capricorn at lat. 23 1-2°S. ..... Click the link for more information.

), and the Arctic Circle Arctic Circle, imaginary circle on the surface of the earth at 66 1-2°N latitude, i.e., 23 1-2° south of the North Pole. It marks the northernmost point at which the sun can be seen at the winter solstice (about Dec. ..... Click the link for more information. (66 1-2°N) and the Antarctic Circle Antarctic Circle, imaginary circle on the surface of the earth at 66 1-2°S lat., i.e., 23 1-2° north of the South Pole. It marks the southernmost point at which the sun can be seen at the winter solstice (about June 22) and the northernmost point of the southern polar ..... Click the link for more information. (66 1-2°S), marking the farthest points north and south of the equator where the sun appears above the horizon each day of the year (see also midnight sun midnight sun, phenomenon in which the sun remains visible in the sky continuously for 24 hr or longer, occurring only in the polar regions.

The midnight sun is due to the fact that the plane of the earth's equator is tilted about 23 1-2° to the plane of the ecliptic (the ..... Click the link for more information. ). Parallels of latitude and meridians of longitude longitude , angular distance on the earth's surface measured along any latitude line such as the equator east or west of the prime meridian. A meridian of longitude is an imaginary line on the earth's surface from pole to pole; two opposite meridians form a great circle dividing ..... Click the link for more information. together form a grid by which any point on the earth's surface can be specified. The term latitude is also used in various celestial coordinate systems (see ecliptic coordinate system ecliptic coordinate system, an astronomical coordinate system in which the principal coordinate axis is the ecliptic, the apparent path of the sun through the heavens. The ecliptic poles are the two points at which a line perpendicular to the plane of the ecliptic through the ..... Click the link for more information. ).

latitude Rainforests: Self-sustaining Ecosystems | Biodiversity | RESET.org  buck82 The term primary rainforest refers to untouched, pristine forest that exists in its original condition i.e.its development has not been perceptibly influenced by man. Everything else is secondary rainforest, which has been disturbed in some way, naturally or unnaturally. 48 percent of all forests are located in the tropics or subtropics. The tropical forests are located between the tropics of Cancer and Capricorn, about 23.5 degrees latitude north and south , respectively. With around 18.5 million square kilometres, they cover around 40 percent of the tropical land area. When rainfall is high and evenly distributed throughout the year (at least 2000 mm/yr or 100 mm/month), evergreen rainforests develop, forming the core of the tropical swath along the equator. Home to the world’s most lush and diverse flora and fauna, this region has almost daily rainfall. Even though tropical rainforests cover only some 11.5 percent of the world’s surface, they store in their biomass over half of the world’s rainfall.

tauntingpanda Self-contained Ecosystems Three quarters of the soil in the tropics is very low in nutrients. It is very old and therefore much of its mineral content is already washed out. The fact that rainforests can exist despite infertile soil is due to a perfectly balanced, inbuilt recycling system. First, fallen leaves, dead animal and plant matter decompose on the topsoil. Countless small animals, fungi and bacteria seize upon the organic material and decompose and mineralise it in a short period of time so that plant roots can absorb the nutrients. In order to maximise absorption, many trees have a shallow and effective network of roots, some of which even grow upward. Fungi play a very important role in this recycling system. Using the fine tree roots, they enter into a symbiosis called Mycorrhiza. Together, they form an extremely effective circulation system of nutrients that maintains the minerals in circulation too. The fungi make it easier for the tree roots to absorb the minerals and in return they receive carbohydrates from the tree, produced in the leaves through photosynthesis.

Large-scale felling of trees leaves has a destructive effect on this process: the Mycorrhiza is destroyed, the nutrients flow away and become forever lost to the system. How low the nutrient content of the soil is can be measured by the supply of nitrogen in the soil. In Central Europe, 94 percent of the nitrogen supplies exist in the soil and only six percent are contained in the biomass. It's quite the contrary in the tropics: here more than half--58 percent to be precise-- of nitrogen supplies are stored in the plants, while 42 percent are found in the soil. High insulation year-round, favourable climate conditions, uninterrupted cycles and maximum biodiversity mean our current tropical forests have some of the highest volumes of biomass on earth. Tropical rainforests contribute 29 percent of the earth’s total foliage biomass. Three out of four of the currently known 1.85 million species come from the tropics. In one square kilometre of forest in Panama, 41,000 insect species were counted!

Self-sufficient Water Use The rainforest receives between one quarter and, at most, one half of the water it requires from rainfall with the lion's share of its water needs being met via its own micro-water cycle. In the rainforest, large amounts of water evaporate and form mighty rain clouds. These rain down over the forest and then evaporate, ready to repeat the cycle. Sufficiently large and interrelated forest areas are needed in order for the micro-water cycle to be self-sustaining, meaning, naturally, that deforestation plays a significant role in this process. Model calculations assume that the micro-water system functions as long as at least 50 percent of the original forest area available was in existence before the start of deforestation. Experts thus fear that a chain reaction could be triggered: if the micro-water cycle is even delicately disturbed, it could completely collapse. The forests wouldn’t have the necessary water, which could accelerate the deterioration of tropical forests. Rainforest Action Network Away from The Equator The tropical moist forests or seasonal rainforests link together the evergreen rain forests to the north and south.

Seasonal fluctuations increase in intensity as one moves away from the equator with some seasonal rainforests experiencing dry periods of 2 to 5 months. As one moves towards the poles, the seasonal rainforests merge smoothly into seasonal dry forests. Here, dry periods last longer, rainfall decreases and seasons become more clearly defined. Gradually, the seasonal dry forests become superseded by savannas and forests of cactus. In coastal regions, one finds a special type of tropical forest: the tidal forest or the so-called mangrove forest. Mangroves ultimately carve out their own ever-growing habitat. The roots of these mangroves grow in sedimentary depositional environments. In the process, the mangrove’s dense network of roots acts as mechanism to catch the silt. Once the process is initiated, more and more silt accumulates. The process is impeded, above all, when sediment is washed away by tidal currents. Natural Air Filtering Tropical rainforests store vast amounts of the greenhouse gas carbon dioxide. It is stored in forest biomass as well as in the soil. Estimates start at 375 billion tonnes of carbon. Through burning and rotting, the carbon dioxide in the biomass is released into the atmosphere.

It is estimated that through deforestation, tropical rainforests release between 0.6 and 2.6 billion tons of greenhouse gas per year. Every year approximately 22 billion tonnes of carbon dioxide are emitted worldwide from various sources. The Big Picture: Our Depleting Forest Cover At the beginning of the 21st century, 39 million square kilometres of the Earth’s surface was covered with forest, some 19 million of which was tropical forest. In the middle of the last century that figure was almost double! The loss of forest area continues: today, on average, over 415 square kilometres of tropical rainforest is deforested daily. That is equivalent to an area larger than the city of Munich. Between 1990 and 2000 alone, around 900,000 square kilometres of tropical forest was irretrievably lost. Commercial logging for lumber production, which is almost exclusively used for export, but also for firewood, is one of the most important factors causing deforestation. The exploitation of the land for agriculture is another.

On the one hand, plantations arise for the cultivation of highly exportable products (cash-crops) like soy, coffee, sugarcane, cacao, palm oil or oranges. On the other hand, grasslands are created for the farming of livestock. The traditional system of shifting cultivation itself exacerbates the problem. In its prevailing form, shifting cultivation hardly corresponds to the small-allotment, slash and burn practice of the original inhabitants. Much more common today is deforestation, by numerous landless settlers, of unregulated parcels of land in order to cultivate food for their own personal needs. Due to the quickly exhausted soils, which don’t permit lasting usage or steady yields, the settlers move along after a short time to deforest other still-fertile areas. Various infrastructure projects also contribute to the deterioration of tropical forests. The building of settlements, transportation routes or industrial facilities is analogous to the construction of reservoirs for hydroelectric power stations. Here, rapid deforestation occurs in order to enable the reduction of mineral resources like copper, nickel, manganese, gold or iron ore. As a measure to preserve valuable ecosystems and tropical rainforests, the designation of protected area has proven effective.

At the turn of the century, around 12, 750 protected areas constituted over 12 million protected square kilometres, 30 percent of which are national parks. Source links

Question: The Tropics of Cancer and Capricorn are respectively (what number)-and-half degrees north and south of the Equator?
Answer: 23