Whiteout | Definition of Whiteout by Merriam-Webster Definition of whiteout : a surface weather condition in a snow-covered area (as a polar region) in which no object casts a shadow, the horizon cannot be seen, and only dark objects are discernible; also : a blizzard that severely reduces visibility Examples of whiteout in a sentence We got caught in a whiteout. Origin and Etymology of whiteout white + blackout white-out (cover) - Memidex dictionary/thesaurus Merriam-Webster: whiteout a surface weather condition in a snow-covered area (as a polar region) in which no object casts a shadow, the horizon cannot be seen, and only dark ... (27 of 66 words, pronunciation) American Heritage Dictionary: whiteout A polar weather condition caused by a heavy cloud cover over the snow, in ... | A fluid, usually white, that dries quickly and is applied to printed ...

(27 of 65 words, 2 definitions) white-out > white-out Explanation: Poate lingvistii nu vor fi de acord, dar asa spun alpinistii Acest termen nu a fost utilizat până acum în literatura noastră de munte. Eu cel puţin nu l-am întâlnit. Vă veţi da însă imediat seama ca v-aţi întâlnit uneori, iarna, pe munte, cu acest fenomen, pe care francezii îl numesc blanc total, tradus se pare din literatura anglo-saxonă unde este consacrat de mult timp termenul de white-out. Dicţionarele Chambers (ediţie 1992) îl definesc astfel: "Fenomen ce apare în regiuni înzăpezite, pe timp de ceaţă sau cer acoperit, condiţii în care pământul şi cerul fuzionează într-un tot albicios (in a single whiteness)".

Traducerea cuvânt cu cuvânt a lui white-out prin alb total, sau alb complet, nu sugereaza prea bine fenomenul. Termenul englez pare mai adecvat (şi francezii îl folosesc deseori netradus), căci out are sensul de complet, total dar şi sensul de afară. Pentru a apare, white-out-ul necesită existenţa, simultană, a două elemente: sol complet acoperit de zăpadă, a cărui întreagă întindere vizibilă să aibă suprafaţa uniformă (nevălurită şi neîntreruptă de vegetaţie, pietre, stânci, stâlpi de marcaj, urme de paşi sau schiuri etc.); cer de culoare uniformă şi perfect identică zăpezii. Aceste condiţii se întrunesc mai ales dacă este ceaţă.

Atunci, "cerul" (ceaţa) are culoarea "solului" (zăpezii), încât nu putem identifica linia de demarcaţie, iar suprafaţa de zăpadă pe care am putea-o distinge este redusă la câţiva metri sau zeci de metri, astfel că sunt mari şanse să fie perfect uniformă, fără vreun detaliu vizibil. Asemenea situaţii putem întâlni frecvent în Carpaţi, pe timp de iarnă, mai ales în golul alpin. In acea zi (duminica, de Paşti) ne-a arătat Ducu fenomenul "white out" (din cate am inteles eu e o iluzie optica in care nu se mai distinge limita dintre cer si pamant) , un alb unitar, dar si periculos care a adus multe probleme impatimitilor muntzomani. Sper sa-ti fie de folos linkurile.

Succes -------------------------------------------------- Note added at 17 mins (2004-12-10 11:28:30 GMT) -------------------------------------------------- Dupa cum vedeti, este vorba de acea iluzie optica prin care nu se mai distinge cerul de pamant, deci nu este acelasi lucru cu ninsoarea abundenta. De fapt, nu este vorba de ninsoare, ci doar de culoarea zapezii si culoarea cerului - fiind una si aceeasi, exploratorul nu mai poate deosebi cerul de pamant, deci nu se mai poate orienta. -------------------------------------------------- Explanation: Définition : 1.((...)) condition in which the contours and natural landmarks in a snow-covered region become indistinguishable. The associated meteorological conditions appear to be a uniform layer of relatively low cloud; under such conditions the light which reaches the surface arrives in nearly equal measure from all directions, with a resulting absence of shadows. 2.

A surface weather condition in an artic area in which no object casts a shadow, the horizon cannot be seen, and only dark objects are discernible and which is caused by heavy cloud cover over a snow surface so that light coming through the clouds is essentially equal to the light reflected off the snow. 3. In FRANCEZA= blanc dehors n. m. ; voile blanc n. m.; jour blanc 4. Ramane de vazut care dintre variantele in ROMANA este ok....avand in vedere ca este un fenomen specific zonei Polului Nord... Explanation: Poate lingvistii nu vor fi de acord, dar asa spun alpinistii Acest termen nu a fost utilizat până acum în literatura noastră de munte. Eu cel puţin nu l-am întâlnit. Vă veţi da însă imediat seama ca v-aţi întâlnit uneori, iarna, pe munte, cu acest fenomen, pe care francezii îl numesc blanc total, tradus se pare din literatura anglo-saxonă unde este consacrat de mult timp termenul de white-out.

Dicţionarele Chambers (ediţie 1992) îl definesc astfel: "Fenomen ce apare în regiuni înzăpezite, pe timp de ceaţă sau cer acoperit, condiţii în care pământul şi cerul fuzionează într-un tot albicios (in a single whiteness)". Traducerea cuvânt cu cuvânt a lui white-out prin alb total, sau alb complet, nu sugereaza prea bine fenomenul. Termenul englez pare mai adecvat (şi francezii îl folosesc deseori netradus), căci out are sensul de complet, total dar şi sensul de afară.

Pentru a apare, white-out-ul necesită existenţa, simultană, a două elemente: sol complet acoperit de zăpadă, a cărui întreagă întindere vizibilă să aibă suprafaţa uniformă (nevălurită şi neîntreruptă de vegetaţie, pietre, stânci, stâlpi de marcaj, urme de paşi sau schiuri etc.); cer de culoare uniformă şi perfect identică zăpezii. Aceste condiţii se întrunesc mai ales dacă este ceaţă. Atunci, "cerul" (ceaţa) are culoarea "solului" (zăpezii), încât nu putem identifica linia de demarcaţie, iar suprafaţa de zăpadă pe care am putea-o distinge este redusă la câţiva metri sau zeci de metri, astfel că sunt mari şanse să fie perfect uniformă, fără vreun detaliu vizibil.

Asemenea situaţii putem întâlni frecvent în Carpaţi, pe timp de iarnă, mai ales în golul alpin. In acea zi (duminica, de Paşti) ne-a arătat Ducu fenomenul "white out" (din cate am inteles eu e o iluzie optica in care nu se mai distinge limita dintre cer si pamant) , un alb unitar, dar si periculos care a adus multe probleme impatimitilor muntzomani. Sper sa-ti fie de folos linkurile. Succes -------------------------------------------------- Note added at 17 mins (2004-12-10 11:28:30 GMT) -------------------------------------------------- Dupa cum vedeti, este vorba de acea iluzie optica prin care nu se mai distinge cerul de pamant, deci nu este acelasi lucru cu ninsoarea abundenta.

De fapt, nu este vorba de ninsoare, ci doar de culoarea zapezii si culoarea cerului - fiind una si aceeasi, exploratorul nu mai poate deosebi cerul de pamant, deci nu se mai poate orienta. -------------------------------------------------- Note added at 4 hrs 47 mins (2004-12-10 15:57:41 GMT) -------------------------------------------------- Mai dau un citat luat de la primul link, cu riscul de a va plictisi, dar mie mi se pare chiar foarte interesant fenomenul: ...În condiţii de white-out nu mai există repere, nici măcar \"cer\" şi \"pământ\". \"Actorii\" de pe această scenă vor avea nu numai probleme de orientare (busola e obligatorie pentru păstrarea direcţiei generale) ci şi de confort psihic şi de menţinere a echilibrului.

Omul se simte \"suspendat\" într-un cer înnorat sau \"scufundat\" într-o mare lăptoasă. Nu există orizont. Se pierde simţul de \"deasupra\" şi de \"dedesubt\", de \"vertical\" şi \"orizontal\". În white-out nu se mai pot evalua distanţele. Un mic detaliu din teren, ce pare mare şi departe, la zeci sau sute de metri, se dovedeşte a fi la câţiva paşi de noi şi mult mai mic... whiteouts > correcciones con líquido corrector (blanco) correcciones con líquido corrector (blanco) Explanation: whiteout, por derivación de su significado original, se utiliza para referirse a las correcciones en notas o documentos hechos con líquido corrector. No existe una palabra única en español. Definiciones: A noun 1 whiteout an arctic atmospheric condition with clouds over snow produce a uniform whiteness and objects are difficult to see; occurs when the light reflected off the snow equals the light coming through the clouds.

Etymology: white + blackout : a surface weather condition in a snow-covered area (as a polar region) in which no object casts a shadow, the horizon cannot be seen, and only dark objects are discernible; also : a blizzard that severely reduces visibility -------------------------------------------------- Note added at 11 hrs 26 mins (2005-04-04 05:20:22 GMT) -------------------------------------------------- NOTA/Aclaración. no...whiteouts significa \"sin correcciones con líquido corrector\". Pero la pregunta es sólo sobre la palabra \"whiteouts\", que significa \"correcciones con líquido corrector\". whiteout whiteout Loss of orientation with respect to the horizon caused by sun reflecting on snow and overcast sky. Military dictionary. 2000.

white propaganda Look at other dictionaries: Whiteout — or white out may refer to:*Whiteout (weather) *Correction fluid **Wite Out, a line of correction fluid *Winnipeg White Out, a hockey tradition started by fans of the Winnipeg Jets * Whiteout (2000 film), a Japanese film directed by Setsurou… … Wikipedia Whiteout — auf dem Ekström Schelfeis, Antarktis Ein Whiteout ist ein meteorologisches Phänomen, das vor allem in Polargebieten und im Hochgebirge auftritt. Als Whiteout wird die Helligkeit beschrieben, die bei schneebedecktem Boden und gedämpftem… … Deutsch Wikipedia Whiteout — Saltar a navegación, búsqueda La masa de tierra más aislada del planeta. 90° latitud sur, cero longitud este. Diez millones de kilómetros cuadrados de hielo. Seis meses de oscuridad. Las temperaturas llegan a 50 grados bajo cero. Los vientos… … Wikipedia Español whiteout — [hwīt′out΄, wīt′out΄] n. Meteorol.

an optical phenomenon, usually in polar regions, in which the snow covered ground blends into a uniformly white sky, greatly reducing the visibility of shadows, clouds, the horizon, etc. and one s sense of… … English World dictionary Whiteout — Cette page d’homonymie répertorie les différentes œuvres portant le même titre. Whiteout est l’appellation anglophone du phénomène climatique de blanc dehors. Plusieurs œuvres portent ce titre : Sommaire 1 Littérature et bande dessinée … Wikipédia en Français whiteout — UK [ˈwaɪtaʊt] / US [ˈwaɪtˌaʊt] / US [ˈhwaɪtˌaʊt] noun [countable] Word forms whiteout : singular whiteout plural whiteouts a situation in which there is so much snow and low cloud that you cannot see clearly … English dictionary whiteout — /hwuyt owt , wuyt /, n. 1. Meteorol. a. a condition, found in polar regions, in which uniform illumination from snow on the ground and from a low cloud layer makes features of the landscape indistinguishable. b.

a condition of heavily falling or… … Universalium whiteout — orientacijos praradimas statusas T sritis Gynyba apibrėžtis Orientacijos pagal horizontą praradimas dėl saulės atspindžio nuo sniego ar debesų. atitikmenys: angl. whiteout pranc.

voile blanc … NATO terminų aiškinamasis žodynas whiteout — noun Etymology: white + blackout Date: 1942 a surface weather condition in a snow covered area (as a polar region) in which no object casts a shadow, the horizon cannot be seen, and only dark objects are discernible; also a blizzard that severely … New Collegiate Dictionary whiteout — noun a) a heavy snowstorm; a blizzard b) an Arctic condition, caused by diffuse lighting, in which the horizon can not be distinguished and physical features are lost in the background … Wiktionary 16+ FM 34-81-1: Battlefield Weather Effects - GLOSSARY FM 34-81-1: Battlefield Weather Effects GLOSSARY AMSS automated meteorological sensor system AO area of operations ATACMS Army tactical missile systems ASAS All-Source Analysis System ATCCS Army Tactical Command and Control System ATGM antitank guided missile system ATW antitank weapon AVLB armored vehicle launched bridge avn aviation AWS Air Weather Service (USAF) BMCT beginning of morning civil twilight BMNT beginning of morning nautical twilight bn battalion DTSS Digital Topographic Support System DZ drop zone ECB

 echelons corps and below EECT end of evening civil twilight EENT end of evening nautical twilight effect effective FALIIP forward area limited observation program fc footcandle FLOT forward line of own troops FO forward observer HAHO high altitude, high opening HALO high altitude, low opening HC hexachloroethane IEW intelligence and electronic warfare IFV infantry fighting vehicle IPB intelligence preparation of the battlefield IR Information requirement METT-T mission, enemy, terrain, troops, and time available MFF military free fall NATO North Atlantic Treaty Organization NBC nuclear, biological, and chemical nmi nautical mile (distance) R&S reconnaissance and surveillance RC Reserve Component REMBASS Remotely Monitored Battlefield Sensor System rqmts requirements SLAR side looking airborne radar SOF special operations forces SOWT special operations weather team SP self-propelled TOW tube-launched, optically tracked, wire-guided TRADOC US Army Training and Doctrine Command TTP tactics, techniques, and procedures TV television UGDF uniformed gridded data field USAF United States Air Force USAR United States Army Reserve WET weather, enemy, and terrain WETM weather team WTDA weather tactical decision aid WW weather warning Y an unknown amount of time PART 2

 - DEFINITIONS absolute humidity A ratio of the quantity of water vapor present per unit volume of air, usually expressed as grams per cubic meter or grains per cubic foot.

Air Weather Service An Air Force field operating agency reporting directly to the Air Staff. AWS operates centralized weather support and provides technical advice and assistance to USAF weather units in support of USAF and Army missions worldwide. altitude The height measured from MSL. altostratus Clouds that are relatively uniform gray to blue sheets that cover the entire sky. When thin, the sun or moon may be visible as a "bright spot. " Cloud bases range from 6,500 to 20,000 feet AGL. atmospheric pressure The pressure exerted by the atmosphere as a consequence of gravitational attraction exerted upon the column of air laying directly above any point. barometric pressure The measure of atmospheric pressure by a mercurial or aneroid barometer. Changes in pressure are significant in weather forecasting. The normal pressure at sea level is 29.92 inches of mercury or 1013.3 millibars. Rising pressures usually indicated improving weather conditions; falling pressures may reflect impending inclement weather. Barometric pressure is used in aircraft altimeter settings to tell pilots how far above ground level the aircraft is. This is critical for landing during obscured conditions and NOE flying.

battlefield environment A phrase used to describe the combination of weather, terrain, BIC, illumination, and background signatures that occur on a battlefield. belt Weather kit A small kit with simple equipment, used originally by the US Forest Service, and now employed by S2 personnel at maneuver brigades. The BWK equipment measures temperature, dewpoint, pressure, and wind speed and direction. It is slow and does not meet the accuracy standards necessary to support the Army's battlefield weapon systems. The BWK will be replaced by an automated meteorological sensor system (AMSS) blizzard A violent, intensely cold wind of 30 kn or greater with considerable falling or blowing snow causing visibility to drop to .5 miles or less. ceiling (cloud) The height above the earth's surface of the lowest layer of clouds. This layer is reported as broken, overcast, or obscured and not classified as thin or partial. See cloud cover for details. Celsius A temperature scale (formerly called centigrade). The temperature interval between waters ice and steam points is divided into 100 parts (or degrees) with 0o Celsius at the freezing or ice point and 100o at the boiling or steam point. Used commonly worldwide.

cirrocumulus Clouds that are high and thin which appear as small white flakes or patches of cotton. Cirrocumulus clouds are sometimes called a mackerel sky. The bases of cirrocumulus clouds are above 16,000 feet AGL. cirrostratus Clouds that are thin and whitish layers appearing like a sheet or veil. The ice crystals composing these clouds may produce a halo effect around the sun or moon. The bases of cirrostratus clouds are above 16,000 feet AGL. cirrus Clouds that are thin, feather-like ice crystal clouds in patches or narrow bands. Cirrus clouds are sometimes called mares tails. The bases of cirrus clouds are above 16,000 feet AGL, climatology The historical records of weather conditions measured or observed at a specific location is knows as climatology. Some data go back over 100 but generally a 10- to 25-year history is more common. Climatology is useful in planning operations beyond 5 to 7 days. It usually describes the average (or mean) conditions such as high and low temperatures and extremes.

clouds A visible aggregate of minute water and ice or just ice particles in the atmosphere above the surface of the earth. Clouds differ from fog only by definition--fog is in contact with the surface of the earth. cloudburst A sudden and extremely heavy downpour of rain. cloud cover The amount of clouds over, or at, a given location. Cloud conditions are expressed as cloud bases or ceiling, the amount of cover stated in eighths--1/8 to 4/8 described as scattered; 5/8 to 7/8, broken; and 8/8, overcast), and cloud tops. Several layers of scattered clouds added together may result in a broken or overcast condition Low clouds impact many battlefield operations, especially the use of smart weapons. cumulonimbus Clouds that are large, dense, and towering with cauliflower-like tops. The top portion of the cloud is often flattened into an anvil shape. Cumulonimbus clouds are also known as thunderstorms. cumulus Billowy, individual cloud masses that often have flat bases. Bases range from near the surface to 6,500 feet AGL.

density altitude The height above MSL at which the existing density of the atmosphere would be duplicated in the standard atmosphere; atmospheric density expressed as height according to a standard scale. Extremely important in flight operations. dew Water condensed onto grass and other objects near the ground. Occurs when the temperature has fallen below the dewpoint of the surface air (due to radiational cooling during the night) but is still above freezing. If the temperature falls below freezing after dew has formed, the frozen dew is known as white dew. dewpoint The temperature to which a given weight of air must be cooled at constant pressure and constant water-vapor content in order for saturation to occur. When this temperature is below 0o C, (32o F) it is sometimes called the frost point. diurnally Having a daily cycle. drizzle Fairly uniform precipitation composed exclusively of fine drops of water falling very close to one another. dry-bulb temperature The temperature measured by the dry bulb of a psychrometer; ambient air temperature. effective illumination The level of light available for night operations. effective wind speed The combined effect of actual (meteorological) wind and other motion caused by the moving of an object or a person through air.

Also caused by moving equipment such as aircraft propellers or rotors. elevation; station elevation The measure of height with respect to another point on the earth's surface; usually MSL. Fahrenheit A thermometer scale on which the boiling point of water is at 212o and the freezing point is at 32o above zero point. Used primarily in the US. FALOP A program implemented in the 1970's to supplement battlefield observations taken by USAF AWS WETMS. FALOP is employed by S2 personnel at maneuver brigades and battalions. The BWK is used by the S2 to make limited measurements of weather conditions. Additionally, the S2 provides estimates of other weather and environmental conditions he observes. His report is encoded and forwarded to the closest WETM. fallout The precipitation to earth of particulate matter from a nuclear cloud; also applied to the matter itself, which may or may not be radioactive. fog A cloud with its base at or very near the earth's surface. footcandle (fc) A unit of illumination equal to 1 lumen ft-2.

Full sunlight with zenith sun produces an illuminance of the order of 10,000 fc on a horizontal surface. Full moonlight provides an illuminance of about 0.02 fc. Adequate illumination for steady reading is about 10 fc. Close machine work is required about 30 to 40 fc. forecast units USAF WETMs and centers at higher Army echelons that produce support forecasts for planning and operations. frost A feathery deposit of minute ice crystals or grains upon a surface or object, formed directly from vapor in the air; the process by which such ice crystals are formed; any temperature at which frost forms. Frost often forms when the close-lying air is above 0o C (32oF), especially in calm, clear air when radiation or evaporation reduces a surface temperature to or below the freezing point. frostbite The freezing or partial freezing of some part of the human body. frost heaves Also frost thrusting; frost lifting. The upward or sideways movement of surface-soils, rocks, and vegetation through expansion caused by freezing subsurface moisture, soil, and gravel.

gust Rapid fluctuations in wind speed with a variation of 10 knots or more between peaks and lulls. hail Hail is observed precipitation in the form of small balls or pieces of ice (hialstones), falling either separately or agglomerated into irregular lumps. Hail falls during heavy thunderstorms. high In meteorology it is synonymous with "area of high pressure" and refers to a maximum of atmospheric pressure in two dimensions--closed isobars in the synoptic surface chart; or a maximum of height (closed contours) in the constant-pressure chart. Since a high is, on the synoptic chart, always associated with anticyclonic circulation, the term is used interchangeably with anticyclone. humidity A measure of the water vapor content of air. hypothermia Excessive lowering of body temperature generally caused by prolonged exposure to cold or when the body has become wet. Hypothermia can occur at temperatures well above freezing as easily as at temperatures below freezing. icing In general, any deposit or coating of ice on an object; a mass or sheet of ice formed on the ground surface during the winter by successive freezing of sheets of water that may seep from the ground, a river, or a spring.

instrument flight rules An aircraft operational term indicating that the weather conditions have deteriorated to the point that navigational instruments on board the plane must be used in flying from one place to another. inversion (stable) condition An increase in air temperature with an increase in height. The condition is called stable because there is usually little vertical movement of air. knot The unit of speed or distance in the nautical system. One nautical mile per hour. See conversion factors in Appendix P. lapse (unstable) condition A decrease in air temperature with an increase in height. The condition is called unstable because it is accompanied by vertical air movement. light and illumination data Battle planning requires accurate timing based on available light. Light tables have been computed for any location that tell sunrise, sunset, moonrise, moonset, and moon phase. Illumination is a measure of sunlight, moonlight, starlight, and air glow. Illumination is a critical factor in the considered of NVD, cloud cover, and terrain masking. low An area of low pressure referring to a minimum of atmospheric pressure in two dimensions. Since a IOW is, on a weather chart, always associated with cyclonic circulation, the term is used interchangeably with cyclone.

mesoscale Smaller scale weather features that exist for minutes or hours. Examples of mesoscale atmospheric phenomena are thunderstorms, tornadoes, and land-sea breezes. meteorological products Processed information derived from basic meteorological data which is collectively referred to as meteorological products. Such information can be in the form of forecasts, specific data, or WTDAs. WTDAs may correlate one or more data elements impacting a system with critical values, timing, system limitations, and other modifying factors. moderate weather impact A subjective measure of weather conditions impacting a system or operations that require alternative actions to be considered. Moderate impacts limit the effectiveness of the system or operations from 25 to 75 percent. nimbostratus A gray or dark massive cloud layer accompanied by continuous rain or snow. precipitation rates The measured, or estimated, rate of rainfall or snowfall during a given period. Precipitation rates are essential to predict ground moisture, flooding, river crossings, and other trafficabiiity factors. Precipitation rates also affect visibility.

refractive index A measure of the amount of "refraction," or bending, of an energy wave (visual light, infrared, radio and others) passing from one density to another in a medium such as air or water. The apparent bending of a stick when placed in a pool of water is an example. relative humidity Ratio, usually expressed as a percentage of air's water vapor content, to its water vapor capacity at a given temperature and pressure. sea state Also state-of-the-sea. Describes wind-generated waves on the surface of the sea. seeability Distance at which a sensor is able to see, to recognize, or to lock onto a target. Seeability is dependent on the condition of the atmosphere, the contrast between the target and the background, the direction and type of illumination, and the characteristics of the sensor. semidiurnally A cycle occurring approximately every half day. sky conditions The amount of sky covered by clouds or the amount obscured by surface-based phenomena. This information is derived from standard charts. slant-range visibility The distance a pilot can distinguish objects that are both forward and beneath his aircraft. For example, looking down at an angle as he approaches a target or a runway.

sleet A term sometimes used for ice pellets, a mixture of precipitating rain and snow, or glaze. snow Precipitation composed of white or translucent ice crystals, chiefly in complex branched hexagonal form and often agglomerated into snowflakes. soil trafficability The capacity of a soil to withstand traffic, especially the traffic of military vehicles. specific humidity The ratio of the mass of water vapor to the total mass of air (including water vapor). state-of-the-ground A standardized surface observation that describes the condition of the ground surface. Basically, state-of-the-ground is characterized as dry, moist, wet, frozen, and ice or snow covered. Staff weather officer A USAF AWS officer, qualified in forecasting, that usually commands a WETM. tie may be a lieutenant or a colonel depending on the Army unit he is attached to. Some SWOs, assigned to Army commands, serve without a WETM. The SWO, a member of the Army commanders special staff, works under the direction of the G2 or S2. steering wind Winds that are winds measured at 50 feet (16 m), although they may extend as high as 2,500 feet.

They are used in smoke operations where the moving air is measured far enough above the ground to be free of disturbances caused by local terrain variations. They establish the speed and direction of a smoke cloud. Steering winds also play a role in the direction that weather systems move. stratocumulus Clouds having large globular masses or rolls which look like balls of dirty cotton. Stratocumulus form from the breaking up of a stratus layer or from the spreading out of cumulus clouds. Bases range from near the surface to 6,500 feet AGL. surface observations Weather and environmental observations measured or estimated on the land or water surface, and usually reflecting surface conditions. Cloud cover is an exception. surface winds Wind speed, direction, and gust speeds measured over the land or water. Technically measured at 10 meters above the surface. synoptic scale Large-scale atmospheric features that exist for days or weeks. An example of synoptic scale is the analysis of weather fronts, highs, and lows over the continental us. temperature A measure of the hotness or coldness of the air near the surface (surface ambient temperature), the ground (surface or ground temperature), or the upper atmosphere (air temperature).

Measured by a thermometer or other instrument. temperature gradient The change in temperature per unit of distance between one point and another. temperature-humidity index An indicator of the effect of temperature and humidity upon individuals. Sometimes called the misery index by television weatherpersons. An example is the WBGT index. temperature inversion See inversion condition. thaws A weather condition occurring when the temperature rises above the freezing point and ice and snow melt. tidal current The alternating horizontal movement of water associated with the rise and fall of the tide. In relatively open locations, the direction of tidal currents rotates continuously through 360 degrees diurnally or semidiurnally. In coastal regions, the nature of tidal currents is determined by local topography as well. tide The periodic rising and falling of the oceans, large lakes, and the atmosphere. [t results from the tide-producing forces of the moon and sun acting upon the rotating earth. This disturbance actually propagates as a wave through the atmosphere and through the surface layer of the oceans. turbulence A condition of The atmosphere in which air currents vary greatly over short distances. Turbulence may occur at any altitude, and the intensity may vary rapidly over short distances. See wind shear.

twilight The periods of incomplete darkness following sunset (evening twilight) or preceding sunrise (morning twilight). Twilight is designated as civil, nautical, or astronomical, as the center of the sun travels 6, 12, or 18 degrees below the celestial horizon, respectively. In general, civil twilight precedes nautical twilight by 2 hours. visual flight rules In aviation a set of regulations that must be adhered to when piloting in calm, clear weather where the pilot can move from one point to another using ground features for navigational aids. USAF tactical weather support As directed by AR 115-10/AFR 105-3, the USAF AWS provides part of the Army's tactical weather support. This includes the collection of surface weather data up to the division command elements and the production of forecasts and climatic data, The Army has the greater role in its own weather support. The Army collects surface weather forward of the division command elements, and all upper air weather data needed to support its tactical operations. Additionally, the Army provides the USAF WETM the communications paths and equipment to pass weather information to the Army users.

visibility The greatest distance that prominent objects can be seen and identified by the unaided, normal eye. When NVG or other infrared devices are used to increase visual distance, "seeability" is used instead of visibility. weather advisory (WA) A special WETM notice when an established weather condition that could affect operations is occurring or is expected to occur. weather briefing Information concerning the current and forecast weather conditions impacting an AO. The SWO, or a member of the WETM or the G2 or S2 may provide weather briefings. Suggested formats are included in Chapter 4. weather effects The impacts, favorable or unfavorable, weather conditions have on tactical systems, operations, personnel, and logistics. Weather effects become highly significant information when they can be cross-checked with specific critical values, reaction leadtimes, and other operational considerations. There are always weather effects that will have an impact on systems or operations. There is no such thing as an all-weather system. weather elements Weather elements (such as wind speed and temperature) are generally benign. Only when they fall below or exceed certain pre-established thresholds do they have an adverse impact on operations, systems, and personnel. These pre-established thresholds are known as critical values.

Critical values change by type of operations, sensitive (or complexity) of systems, and the amount of exposure of personnel to the elements. S2s must know the critical weather values for their unit's operations, systems and personnel and advise the commander and staff when these values are (or will be) reached or exceeded. weather forecast A prediction made by USAF WETMS for periods as short as 3 hours to as long as 96 hours for specific Aos and Ais. Forecasts are correlated with WTDAS to provide tailored products for the supported command's planning, The accuracy of a weather forecasts depends on the timeliness, accuracy, and resolution of the data it is taken from. The longer the period of time a forecast covers the less accurate it becomes. Forty-eight to 96-hour forecasts are considered "outlooks"--or very general forecasts. Beyond 96 hours, climatology is used. weather forecaster A USAF AWS officer or NCO trained in meteorology and forecasting. He uses general area forecasts produced by USAF AWS weather centers, and fine tunes them for his own AO. The forecaster need timely, accurate data from the supported unit's AO and AI to do this fine tuning.

weather observer A USAF AWS officer or NCO trained in meteorology and weather observing. Many AWS NCOS are dual qualified as observers and forecasters and are called weather technicians. The training of an AWS weather observer is technical, S2s are instructed by AWS observers on how to take weather observations. But the observations may fall short of the AWS standard and are, therefore, characterized as "limited." weather tactical decision aids These refer to the manual lookup tables and matrices in this manual, or are computer-driven algorithms by which such a product is generated. These tables provide the critical thresholds that effect operations, systems, and personnel adversely. The tables, together with a current forecast, are used to brief the commander and staff. weather warning (WW) A special notice from the supporting WETM when an established weather condition of such intensity as to pose a hazard to property or life is occurring or is expected to occur. Protective action must be taken. weather watch A special WETM notice alerting the command of the potential for tornadoes, severe thunderstorms, or a winter snow with heavy snow, freezing precipitation, or blizzard conditions. wet bulb globe temperature index A measure of heat stress potential.

It is calculated by using a formula which considers relative humidity, radiant heat, air temperature, and air movement. whiteout Also known as milky weather. A condition in the polar regions in which no object casts a shadow, the horizon becomes indistinguishable, and light-colored objects are very difficult to see. A whiteout occurs when there is complete snow cover, and the clouds are so thick and uniform that light reflected by the snow is about the same intensity as that from the sky. windchill factors These factors are revised temperature values based on the effect of wind and temperature combined on exposed skin. This windchill temperature is the effective temperature for troops. The effect of windchill differs individually because of body chemistry, but is an acceptable operating standard. winds aloft The flow of air, measured in speed and direction above the surface. There is no distinct demarcation between winds aloft and surface winds, although winds above 100 meters are usually referred to as winds aloft. wind shear The rate of change of wind velocity (speed or direction)with distance. Eddies and gusts form in areas of wind shear, thus producing turbulent flying conditions. Wind shear may occur in either the vertical or horizontal plane.

wind speed The rate of movement of air flow. Wind speed is normally reported in nautical miles per hour, or knots. Wind speed is affected by terrain and obstacles such as buildings and trees. NEWSLETTER

Question: What is the name of a surface weather condition in a snow-covered area in which no object casts a shadow, and only dark objects can be seen?
Answer: White-out