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150 Cards in this Set
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What is the relationship betweensemi-permanent subtropical anticyclones and the location of the world’ssubtropical deserts? |
The world’s deserts are located under the eastern flanks of subtropicalanticyclones. The eastern flanks feature extensive areas of subsiding air whichundergoes compressional warming, creating widespread areas of relatively lowhumidity and generally fair skies. |
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How are the trade winds and westerlies linked to the semi-permanentsubtropical anticyclones? |
. The surface winds surrounding asemi-permanent subtropical anticyclone blow clockwise and outward in theNorthern Hemisphere when viewed from above. These winds form the westerlies andtrade winds. |
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Describe the weather along the intertropical convergence zone (ITCZ). |
The intertropical convergence zone (ITCZ) marks the confluence of thetrade winds of the Southern and Northern Hemispheres. The ITCZ is adiscontinuous band of thunderstorms. |
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How do the Aleutian and Icelandic lows change between winter and summer? |
The Icelandic low deepens inwinter and greatly weakens in the summer. The Aleutian low is well developed inthe winter, but disappears in the summer. |
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Why does the climate of SouthernCalifornia feature a wet winter and dry summer? |
Southern California is under the influence of the eastern flank of theHawaiian high in the summer, bringing dry weather. In winter, the high shiftsequatorward causing the rainy season. |
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How are the subtropical gyres of the ocean basins associated with theprevailing planetaryscale wind belts? |
The trade winds and thewesterlies associated with the semi-permanent subtropical highs drive thesubtropical gyres. |
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Describe the seasonal shifts in the latitude of the polar front and thesemi-permanent subtropical highs. |
The polar front and the subtropical highs essentially follow the Sun,shifting poleward in spring and equatorward in fall. |
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What factors contribute to thedevelopment of the Southwest Monsoon? |
The Southwest Monsoon originatesover northern Mexico during May and June and is actually the northern extensionof the Mexican monsoon, which is fed by moisture from the Gulf of Californiaand the Gulf of Mexico. The monsoon develops when intense solar radiationalheating of the ground raises the temperature of the overlying air and creates athermal low. Meanwhile, a monsoon high forms in the middle and uppertroposphere. A low-level horizontal pressure gradient directed from sea to landallows warm, humid air to move inland, leading to considerable cloudiness andrainfall. The circulation about the monsoon high advects moisture northward. |
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Explain the association between weather extremes and a blocking patternin the westerlies. |
Blocking systems prevent the usual west to east movement of weathersystems, causing weather patterns to persist for extended periods of time,sometimes several weeks or longer. This can cause weather extremes, such asfloods, droughts, or excessive heat or cold. |
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Why does a jet stream occur over the polar front? |
The polar front marks a narrowzone of transition between warm and cold air masses. Air pressure drops morerapidly in the vertical in the cold air mass than in the warm air mass,creating horizontal pressure gradients at upper levels. In response to thehorizontal pressure gradients, air moves from higher pressure in the warm aircolumn to lower pressure in the cold air column. With movement, the air isdeflected by the Coriolis Effect, which causes it to turn and blow parallel toisotherms and the polar front. |
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The average temperaturecontrast between winter and summer is greater for continental polar air thanfor maritime tropical air. Explain why. |
In the winter, continentalpolar (cP) air is very cold because daylight is short, solar radiation is weak,the ground is usually snow covered, and radiational cooling is extreme. In thesummer when daylight increases and the ground is free of snow, cP air is mild.The source region for maritime tropical air is tropical and subtropical oceans,which allow the air mass to retain its warm, humid characteristics year round. |
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Identify the various processesthat could be involved in the modification of air masses. |
Air mass modification canoccur by an exchange of heat and/or moisture with the surface over which theair mass travels, radiational heating or cooling, and adiabatic heating orcooling associated with large-scale vertical motion. |
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Over the Great Plains andMidwest, Pacific air is relatively mild and dry. How does Pacific air acquirethese characteristics if it originated over the Pacific Ocean? |
Pacific air is subjected tolarge-scale expansional cooling and compressional warming as the air mass isforced to alternately ascend and descend mountain slopes as it moves from westto east across western North America. On the windward sides of mountains itcools as it rises, becomes saturated, clouds form, and precipitation occurs,thereby reducing the amount of water vapor in the air. On the leeward sides ofmountains it descends, becomes unsaturated as remaining clouds evaporate, andwarms at the higher dry adiabatic rate. Consequently, Pacific air is relativelymild and dry when it descends onto the western plains. |
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The cloud and precipitationpattern associated with a cold front is usually narrower than the cloud andprecipitation pattern associated with a warm front. Explain why. |
The slope of a cold frontalsurface is significantly steeper than that of a warm frontal surface. Thissteep cold frontal slope, combined with a faster forward motion of the surfacefront, along with the flow aloft, enhances uplift, thereby restricting cloudsand precipitation to a narrow zone near the cold front’s leading edge. |
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What conditions in the uppertroposphere contribute to surface cyclogenesis? |
Surface cyclogenesis typicallytakes place directly under an area of upper-tropospheric horizontal divergence.The strongest divergence aloft occurs to the east of an upper-level trough andunder the left-front quadrant of a jet streak. |
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Describe the generalweather conditions in the southeast sector of a typical mature extratropicalcyclone. |
. The southeast sector of aNorthern Hemisphere Extratropical cyclone, known as the warm sector, containsthe mildest air as south and southeast winds advect warm, moist air northward.Skies are generally partly cloudy, dewpoints are high, and scattered convectiveshowers, triggered by solar heating, are possible. |
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Along the path of a matureextratropical cyclone, where is snowfall most likely? |
Snowfall is most likely in thenorthwest sector of a mature extratropical cyclone. |
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What is the relationshipbetween an Arctic high and an Arctic air mass? |
An Arctic high originatesin a source region of an Arctic air mass. |
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Why is a Chinook wind both warmand dry? |
A chinook occurs because ofdescending unsaturated air, typically above the leeward slopes of a mountainrange. The sinking air is warmed by compression. As its temperature increases,its saturation vapor pressure increases while its actual vapor pressure remainsthe same, causing its relative humidity to decrease. |
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What is the principal forcethat drives a katabatic wind? |
Gravity drives a katabaticwind. |
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Brieflydescribe the characteristics of the mature stage of the life cycle of athunderstorm cell. |
The mature stage begins when precipitation develops and thesystem exhibits both an updraft and downdraft. Lightning, thunder, strong gustywinds, and perhaps hail occur during the mature stage. Under extremeconditions, tornadoes might develop. |
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Distinguishbetween a roll cloud and a shelf cloud. |
Aroll cloud is a long, tube-shaped cloud that rotates slowly about itshorizontal axis. Roll clouds occur behind a gust front and beneath but notattached to the cumulonimbus cloud, and are seldom accompanied by severeweather. Shelf clouds are long, wedge-shaped clouds that have a flat base.These clouds appear at the edge of a gust front and beneath and attached to thecumulonimbus cloud. These clouds are associated with damaging winds and occasionallya severe thunderstorm. |
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What causes the anvil top of a cumulonimbus cloud? |
Strongwinds at high altitudes help shape the anvil top of a thunderstorm cloud. Theflat top of the anvil is produced when the rising cloudy air encounters the verystable air of the tropopause and lower stratosphere. The anvil is composedexclusively of ice crystals that are responsible for its fibrousappearance. |
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Distinguishbetween two types of multi-cellular thunderstorms. |
Squalllines and mesoscale convective complexes (MCCs) are two examples ofmulti-cellular thunderstorms. A squall line is an elongated cluster of intensethunderstorm cells that is accompanied by a gust front at the leading edge. Itis found parallel to and up to 300 km ahead of a fast moving, well-defined coldfront. By contrast, a MCC is a nearly circular organized cluster of manyinteracting thunderstorm cells with a life expectancy of at least 6 hrs andoften 12 to 24 hrs. MCCs cover an area of many thousands of square kilometers andtypically occur at night, in the warm season, over the eastern two-thirds ofthe U.S. Unlike squall lines, MCCs develop under weak synoptic flow. |
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Describe how and why thunderstorm frequency varies withEarth’s surface characteristics. |
Thunderstorm frequency is the greatest over the continentalinteriors of tropical latitudes. Thunderstorms are less frequent over surfacesof large bodies of water because the water does not warm as much as land. Inthe subtropics and tropics, intense solar heating combined with convergingsurface winds can trigger thunderstorm development. Mountainous areas alsoreceive many thunderstorms due to topographically related differences inheating. |
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Whyare severe thunderstorms and tornadoes more likely in spring than winter? |
Air masses traveling over cold surfaces in the winter becomemore stable, suppressing convection. Also, solar radiation is less intense inthe winter than in spring. |
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Describethe flash-to-bang method of determining the distance to an approachingthunderstorm cell. |
Thundertakes about 3 seconds to travel 1 km. To use the flash-to-bang method, countthe number of seconds between when lighting is seen and thunder is heard.Dividing this value by 3 seconds will give you the distance in kilometers tothe storm. |
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Inthe coterminous U.S., the number of reports of severe hail increasedexponentially from about 1955-2010. Explain why. |
Theincreased number of hail reports in the U.S. likely can be credited to greaterpublic awareness of hail hazards, improved capabilities of weather radar, theease of reporting hail by way of cell phones, and the National WeatherService’s more aggressive verification of hail reports. |
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Describethe location and significance of tornado alley. |
Tornadoalley extends northward from eastern Texas and the Texas Panhandle throughOklahoma, Kansas, Nebraska, and southeastern South Dakota. Most tornadoes occurin tornado alley. |
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Whatis the basis of the EF-scale? |
TheEF-scale is based on rotational wind speedsestimated from property damage. |
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Ingeneral terms, compare and contrast the weather in the tropics with weather atmiddle latitudes. |
Weatherin the tropics shows little seasonal variation in temperature and moisture,causing little change in surface air pressure. This is opposite from weather atmiddle latitudes, which varies by season. Fronts and frontal weather do notoccur in the tropics due to broad expanses of warm, humid air whereas middlelatitude weather is dominated by air masses with different temperature/humiditycharacteristics separated by weather fronts along which extratropical cyclonesoccur. Afternoon thunderstorms typically occur in the tropics as a result ofintense solar heating. |
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Contrast the characteristics of a hurricane with those of atypical extratropical cyclone. |
Ahurricane is a warm-core low pressure system that forms in a uniform mass ofwarm and humid air, has no fronts, and is about one-third the diameter of atypical extratropical cyclone. Hurricanes spend most of their life cycle overthe ocean. |
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.Describe the typical weather in the eye of a hurricane. |
In the eye of a hurricane, air descends, the sky is nearlycloud-free, and winds are light. |
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Whatthree conditions are required for a tropical cyclone to form? |
Atropical cyclone requires relatively high sea-surface temperatures, asufficient Coriolis Effect to initiate a cyclonic circulation, and relativelyweak winds in the middle and upper troposphere over oceanic hurricane breedinggrounds. |
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Whydoes a hurricane weaken when the system tracks from ocean to land? |
Oncea hurricane moves over land, it begins to dissipate due to a lack of warm,moist air over the ocean needed to sustain a hurricane. Also, winds rapidlydiminish because of greater surface roughness (land versus ocean). |
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Why is the U.S. Pacific coast rarely the target ofhurricanes? |
Most hurricanes that form off the Pacific coast of CentralAmerica track toward the west, away from the U.S. Also, ocean waters off theU.S. Pacific coast are too cold to sustain hurricanes. |
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Whatdistinguishes a tropical depression from a tropical storm? |
. Atropical depression has maximum sustained winds of at least 37 km per hr, and atropical storm has maximum sustained winds of at least 63 km per hr. Once asystem is classified a tropical storm, it is given a name. |
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Identifyand describe the hazards of hurricanes. |
Hazardsof hurricanes are heavy rains and inland flooding, strong winds, tornadoes, andstorm surge. Hurricanes may track well inland, causing persisting heavy rainsthat bring flooding. |
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Whichsector of a land falling hurricane is responsible for the greatest stormsurge? |
Thegreatest storm surge usually occurs on the side of the approaching intensetropical cyclones where the winds are onshore. In the Northern Hemisphere, thehighest storm surge typically occurs to the right of the path of the advancingstorm’s center of lowest surface pressure marked by the eye. |
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Whatis the basis for the Saffir-Simpson Hurricane Wind Scale? |
TheSaffir-Simpson Hurricane Wind Scale is primarily based on maximum sustainedwind speed. |
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What do boundary conditions include? |
The flux of incoming solar radiation, outgoing infrared radiation, Earth's rotation on its axis (the Coriolis Effect), and the physical properties of Earth's surface. |
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Describe a semi-permanent pressure systems. |
Maps of global average air pressure at sea level for January and July reveal several areas of relatively high and low air pressure. |
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Subtropical anticyclones... |
Are imposing features of the planetary-scale circulation centered over subtropical latitudes of the North and South Atlantic, the North and South Pacific, and the Indian Ocean. These highs extend from the ocean surface up to the tropopause, and exert a major influence on weather and climate over vast areas of ocean and continents. |
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What does subsiding air undergo? |
Compressional warming, which produces low relative humidity and generally fair skies. |
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What are the world's major subtropical deserts? |
The Sahara of North Africa and the Sonora of Mexico and southwest US are located under the eastern flanks of subtropical anticyclones. |
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What does a subtropical high feature? |
A weak horizontal air pressure gradient over a broad area surrounding the system's center. Hence, surface winds are very light or the air is calm over extensive areas of the subtropical ocean. |
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In the Northern Hemisphere, viewed from above... |
Surface winds blow clockwise and outward, forming the westerlies and trade winds. |
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Define trade winds. |
Surface winds blowing from the northeast out of the southern flanks of the anticyclones are known as the trade winds. |
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What winds are the most persistent winds on the planet? |
The trade winds. |
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What are the doldrums? |
Trade winds of the 2 hemispheres converge into a broad east-west equatorial belt of light and variable winds. |
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What is the intertropical convergence zone? |
A discontinuous low-pressure belt with thunderstorms paralleling the equator. |
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On the poleward side of the subtropical highs.... |
Surface westerlies flow into regions of low pressure, found primarily over subpolar ocean basins. In the Northern Hemisphere, there are 2 subpolar lows: The Aleutian low over the North Pacific and the Icelandic low over the North Atlantic. |
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Define trade wind inversion. |
A persistent and climatically significant feature of the planetary scale circulation over the easter portion of tropical ocean basins. |
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Surface ocean currents are... |
Wind-driven |
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What characterizes regions where seasonal reversals in prevailing winds cause wet summers and relatively dry winters? |
A monsoon circulation. |
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What do monsoons depend on? |
Seasonal contrasts in the heating of land and ocean surfaces. |
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The ocean has a greater thermal inertia than does....... |
Land |
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Monsoon rainfall is neither _______ or _______ |
Uniform nor continuous. |
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During a monsoon active phase, the weather is mostly.... |
Cloudy with frequent deluges or rain. |
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During a monsoon dormant phase, the weather is.... |
Sunny and hot |
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The westerlies are more vigorous in _______ than in ______ |
Winter - Summer |
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Define blocking system. |
A cutoff Low or a cutoff High that prevents the usual west-to-east movement of weather systems. |
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Any westerly wave pattern, meridional or zonal, can cause what? |
Extremes in weather if the pattern persists for a sufficient length of time. A persistent westerly wave pattern means the same type of air mass advection, the same storm tracks, and basically the same weather type. |
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Cold air is denser than..... |
Warm air so pressure drops more rapidly with altitude in a column of cold air than it does in a column of warm air. |
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Some middle latitude weather extremes such as drought or unusually heavy rainfall are linked to..... |
Episodic sometimes significant changes in atmospheric and oceanic circulation in the tropics. One of the best known of these circulation anomalies occurs in the tropical Pacific nd is known as El Niño. |
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When El Niño trade winds weaken.... |
Seas surface temps rise well above long-term averages over the central and tropical pacific. |
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Define Souther Oscillation. |
A seesaw variation in air pressure across the tropical Indian and Pacific ocean. |
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What are El Niño and the Southern Oscillation known as? Define it. |
ENSO. It is a coupled phenomenon in that its variability in Earth's climate system cannot be explained as exclusively an oceanic or atmospheric event. |
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The net transport of water due to coupling between the surface wind and water is known as.... |
Ekman transport. |
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What does Equatorial upswelling produce? |
A strip of relatively low sea-surface temperatures along the equator from the coast of South America westward to near the International dateline. |
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A link between changes in atmospheric circulation patterns in widely separated regions of the world, often thousands of kilometers apart is known as.... |
Teleconnection. |
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What is North Atlantic Oscillation? |
A seesaw variation in sea-level air pressure between the Azores and Iceland. |
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Define air mass. |
A huge expanse of air covering thousands of square kilometers, is relatively uniform horizontally in temperature and humidity, with both quantities typically decreasing with altitude. |
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Air masses differ not only in temperature and humidity, but also in.... |
Stability. |
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Why does rapid air mass modification occur? |
Because, outside of its source region, polar air is usually colder than the ground over which it travels. |
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What is a front? |
A narrow zone of transition between air masses that differ in density usually because of temperature contrasts. |
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What does a stationary front exhibit? |
Little or no forward movement. |
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What happens if a stationary front begins moving such that the warm air advances while the cold air retreats? |
The front becomes a warm front. |
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When does frontal fog develop? |
When rain falling through the shallow layer of cool air at the ground evaporates and increases the water vapor concentration to saturation. After the warm front finally passes, frontal fog dissipates and skies clear, at least partially, because the zone of overrunning has also passed. The weather tends to become more humid. |
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When does and air mass boundary become a cold front? |
If it begins to move in such a way that the colder air displaces warmer air. |
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What is a squall line? |
A band of intense thunderstorms. |
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Late in its life cycle, an extratropical cyclone moves into colder air and a front forms, known as an occluded front. When does an occluded front form? |
It forms when a faster moving cold front catches up to slower moving warm front. |
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If processes in the atmosphere, such as a region of converging surface winds, increase the density contrast between air masses, what would happen? |
A front forms or grows stronger. This is called frontogenesis. |
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If the density contrast between air masses decreases, perhaps because of diverging surface winds, what happens? |
The front weakens. This process is known as frontolysis. |
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Define an extratropical cyclone. |
A major weather make of middle and high latitudes. |
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Define cyclogenesis. |
The birth of a cyclone, usually takes place along the polar front directly under an area of strong horizontal divergence in the upper troposphere. |
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Some extratropical cyclones continue deepening even after.... |
Occlusion has begun. |
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Define triple point. |
Cold, warm, and occluded fronts intersect at the point of occlusion. |
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Define conveyor belt model. |
Depicts the circulation within a mature extratropical cyclone in terms of three broad interacting air streams, referred to as conveyer belts. |
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An extratropical cyclone has what? |
A cold side and a warm side. |
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A winter storm is an extratropical cyclone that produces what? |
Some combination of frozen or freezing precipitation, including snow, ice pellets (sleet), and/or freezing rain. IN the more intense winter storms, heavy snow combined with low air temperatures and strong wins can produce potentially life-threatening conditions. |
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Define blizzard. |
A severe storm characterized by high winds and reduced visibility due to falling or blowing snow. |
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Define a whiteout. |
When visibility is reduced to the point that it is nearly impossible for a person to distinguish the sky from the ground - everything is white. |
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Define icestorms. |
Form a coating of glaze on cold surfaces that makes for treacherous walking and driving conditions and can bring down tree limbs that sever power lines, causing widespread electrical power outages. |
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What are the necessary ingredients for developing a winter storm? |
Cold a moisture supply, and mechanisms that provide uplift, |
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Define a cold-core cyclone. |
An occluded extratropical cyclone. |
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Define a warm-core cyclone. |
Very shallow, and its circulation weakens rapidly with altitude, that ism away from the immediate heat source. |
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What is an anticyclone? |
Subsiding air and diverging surface winds favor formation of a uniform air mass, no fronts, and generally fair skies. Like cyclones, anticyclones have either cold or warm cores. |
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What is a cold-core anticyclone? |
They exert the highest surface pressures in winter, when associated air mass is coldest and air is most dense. |
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Where do warm -core anticyclones form? |
From south of the polar front and consists of extensive areas of subsiding warm, dry air. |
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What is a Chinook wind? |
A relatively warm and dry downslope winds, usually blowing from the west or southee |
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What is the Santa Ana? |
A hot, dry wind usually blowing from the northeast or east that impacts portions of Southern California from fall into early winter (October-March). |
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Define Katabatic wind. |
A shallow layer of cold, dense air flows downhill under the influence of gravity. |
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What is a haboob? |
The strong, gust downdraft of a thunderstorm generates one of the most spectacular dust storms. |
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When can a heat burst occur? |
If convective rain showers fall from clouds having a high base and relatively dry air below. |
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Define thunderstorm. |
A storm accompanied by lightning and thunder. |
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Define forced convection. |
Frontal or orographic lifting, or converging surface winds strengthen convection. Most thunderstorms are products of forced convection. |
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Define cumulus congestus cloud. |
A cumuliform cloud that shows significant vertical growth and resembles a huge cauliflower. |
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Define a cumulonimbus cloud. |
A thunderstorm cloud with characteristic anvil top, producing precipitation, lightning, and thunder. |
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Define a gust front. |
Miniature cold front that accompanies a storm. |
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Define a roll cloud. |
An elongated, tube-shaped cloud that appears to rotate slowly about its horizontal axis how this cloud forms is not fully understood. |
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Define a shelf cloud. |
Also called an arcus cloud. A low, elongated cloud that is wedge-shaped with a flat base. A shelf cloud is thought to develop from the uplift of stable warm and humid air along the gust front. |
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When does a thunderstorm cell attain a max intensity? |
During its mature stage. Rain is heaviest (especially during the first 5 minutes or so), lightning is most frequent, and hail, strong surface winds, and even tornadoes may develop. |
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What happens during the dissipating stage? |
Subsiding air replaces the updraft throughout the cloud, effectively cutting off the supply of moisture delivered by the updraft. Adiabatic compression warms the subsiding air, the relative humidity below the cloud base decreases, precipitation tapers off and ends, and remaining convective clouds gradually vaporize. |
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A single-cell thunderstorm is usually a relatively weak weather system that.... |
Appears to pop up randomly within a warm, humid air mass. |
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Where are thunderstorms unusual? |
Over coastal areas that are downwind from relatively cold ocean waters. |
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The greater the altitude of the top of a thunderstorm.... |
The more likely it is that the system will p |
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Define wind-shear. |
The change in horizontal wind speed or direction with increasing altitude. |
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Severe thunderstorm cells usually form as part of a.... |
Squalline within the cyclone's warm sector, ahead of and parallel to a fast-moving and well-defined cold front. |
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Severe cells can produce.... |
Large hail, heavy rain, and downbursts. |
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Define lightning. |
A brilliant flash of light caused by an electrical discharge within a cumulonimbus cloud or between the cloud and Earth's surface (the most dangerous case) |
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What is the most common cause of forest fires? |
Lightning. |
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How many forest fires are started by lightning each year? |
9,000 |
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What temp does lightning heat the air along the narrow conducting path? |
The temperatures may exceed 25,000 C. Such intense heating occurs so rapidly that air density cannot respond, at least initially. The rapid rise in air temp is accompanied by a tremendous increase in air pressure locally that generates a shock wave. The shock wave propagates outward, producing sound waves that we hear as the rumble of thunder. |
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How many times faster does light travel than sound? |
A million times faster. That's why we see lightning almost instantaneously, but we hear thunder later. |
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Define downburst. |
An exceptionally strong downdraft that, upon striking Earth's surface, diverges horizontally as a surge of potentially destructive winds. |
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Define macroburst. |
Cuts a swath of destruction over a distance of more than 2.5 miles with surface winds that may top 210 km per hour. |
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Define microburst. |
Smaller and shorter-lived than a macroburst. |
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Define flash flood. |
A short-term, localized, and often unexpected rise in steam level above bankfull, usually because of torrential rain falling over a relatively small geographical area. |
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What time of day are thunderstorms that cause flash floods more common? |
At night. They form in an atmosphere with weak vertical wind shear and abundant moisture through great depths. |
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Because of their design and composition, what type of area is more prone to flash floods during intense downpours? |
Urban areas. |
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What kind of clouds does hail almost always fall from? |
Cumulonimbus. They are characterized by strong updrafts, great vertical development, and an abundance of supercooled water droplets. |
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Of the roughly 10,000 severe thunderstorms that occur in the US in an average year, what percent produce tornadoes? |
10% |
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Define tornado. |
A violently rotating column of air in contact with the ground that is usually produced by a thunderstorm. |
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How are tornadoes often made visible? |
By water droplets formed by condensation and/or by dust and debris drawn into the tornado. |
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What is the most violent of all weather systems? |
Tornadoes |
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Most strong to violent tornadoes are spawned by a highly organized convective system known as.... |
A supercell thunderstorm. |
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Define tropical cyclone. |
Synoptic-scale low-pressure systems that originate over the tropical ocean and include tropical depressions, tropical storms, and hurricanes. |
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What does little variation in the thermal and moisture properties of tropical air mean? |
That there is little horizontal variation in surface air pressure. |
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Define streamline. |
A line drawn on a map that is everywhere parallel to the wind direction, thereby portraying graphically the horizontal flow of air. |
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In what weather does a hurricane develop? |
Hurricanes develop in a uniformly warm and humid air mass, so the system has no associated fronts or frontal weather. |
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Define eyewall. |
A rig of thunderstorm clouds that produce heavy rains and very strong winds. |
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What is the most dangerous and potentially most destructive part of a hurricane? |
The portion of the eye wall on the side of the advancing system where the wind blows in the same direction as the storm's forward motion. |
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Define ring. |
A large turbulent eddy that occurs when a meander in a current forms a loop that pinches off, separating from the main ocean surface current such as the Gulf Stream. |
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Define tropical disturbance. |
If a center of low pressure is detected at the surface. |
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The majority of tropical cyclones that threaten North America develop out of what? |
Connective cloud clusters associated with easterly waves traveling westward of the West African coast. |
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Define Easterly wave? |
A ripple in the tropical easterlies featuring a weak trough of low pressure. |
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Define hot towers. |
Individual towering cumulonimbus clouds on the outer edge or just inside the eyewall and are where most of the hurricane's vertical motion occurs. |
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Define storm surge. |
A dome of ocean water, perhaps 50-100 miles wide that sweeps over the coastline near the hurricane's landfall. |
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What is responsible for storm surge? |
Strong onshore winds plus relatively low air pressure are responsible. |
