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77 Cards in this Set
- Front
- Back
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What is air pressure?
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Air pressure is the weight of the air above a given surface.
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As you climb in elevation, there are _____ air molecules above you, therefore, air pressure ______ ________ with height (and very rapidly)
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As you climb in elevation, there are fewer air molecules above you, therefore, air pressure always decreases with height (and very rapidly)
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When you move air into a column, surface pressure would _______. This process of _______ air pressure causes heat to be released.
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When you move air into a column, surface pressure would increase. This process of increasing air pressure causes heat to be released.
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When you move air out of a column, surface pressure would _______. This process of _______ air pressure causes heat to be released
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When you move air out of a column, surface pressure would decrease. This process of decreasing air pressure causes object to become cold.
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A shorter, colder, denser air mass can exert the same surface pressure as a ____, _____, less ____ air mass.
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A shorter, colder, denser air mass can exert the same surface pressure as a taller, warmer, less dense air mass.
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Atmospheric pressure ______ more rapidly with elevation in a cold column of air and ______ more slowly in a warmer column of air.
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Atmospheric pressure ______ more rapidly with elevation in a cold column of air and ______ more slowly in a warmer column of air.
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Warmer air aloft is normally associated with atmospheric pressure aloft. This results in....?
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Warmer air aloft is normally associated with atmospheric pressure aloft. This results in a more stable atmosphere.
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Colder air aloft is normally associated with atmospheric pressure aloft. This results in....?
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Colder air aloft is normally associated with lowere atmospheric pressure aloft. This results in a more unstable atmosphere.
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What do horizontal temperature differences cause?
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Horizontal temperature differences result in a horizontal difference in pressure, which creates wind (unequal heating of the earth's surface)
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How do we measure air pressure?
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Air pressure is meausured with a barometer (mercurial or aneroid)
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What four things require corrections to be made for accurate air pressure readings?
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temperature, gravity, instrument, *sea level (all of instruments reflect an adjustment for sea level)
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In general, atmospheric pressure decreases __ inch of mercury for each ____ foot rise in altitude.
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In general, atmospheric pressure decreases one inch of mercury for each 1000 foot rise in altitude.
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What is standard atmospheric pressure?
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Standard atmospheric pressure:
29.92"/mercury = 1013.2 millibars = 14.7 lbs per sq in |
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Where are the extremeties of air pressure found?
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Highest air pressure is found in the arctic cold at ~32".
Lowest air pressure is found within hurricanes at ~26"-27". |
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With high pressure, air blows around in a ______ manner in the northern hemisphere and _______ in the southern hemisphere (this is a cross-section). There is surface ___vergence and upper air ___vergence.
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With high pressure, air blows around in a clockwise manner in the northern hemisphere and counterclockwise in the southern hemisphere (this is a cross-section). There is surface divergence and upper air convergence.
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With low pressure, air blows around in a ______ manner in the northern hemisphere and _______ in the southern hemisphere (this is a cross-section). There is surface ___vergence and upper air ___vergence.
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With low pressure, air blows around in a counterclockwise manner in the northern hemisphere and clockwise in the southern hemisphere (this is a cross-section). There is surface convergence and upper air divergence.
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With corrections made to surface pressure readings, surface pressure charts use ______ to depict lines of equal surface pressure.
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With corrections made to surface pressure readings, surface pressure charts use isobars to depict lines of equal surface pressure.
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With isobars, the ____ the lines, the ______ the pressure/winds.
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With isobars, the closer the lines, the greater the pressure/winds.
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Upper air charts are also known as ____ ______ charts.
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Upper air charts are also known as constant height charts.
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Why are upper air charts constructed?
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Upper air charts are constructed to show height variations along a constant pressure height surface.
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Higher heights = ?
Lower heights = ? |
Higher heights = high pressure
Lower heights = low pressure |
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On upper air (constant) charts, height ______lines depict _____.
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On upper air (constant) charts, height contour lines depict pressure.
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What is the most important upper air chart used?
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The 500 millibar chart.
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Newton's First Law of Motion
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An object at rest will remain so and an object in motion will remain so (and will travel at a constant velocity along a straight line) as long as no force is extended on the object.
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Newton's 2nd Law of Motion
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The force exerted on an object equals its mass times the acceleration produced: F=MA
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Newton's 3rd Law of Motion
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To every action there is always an equal and opposite reaction
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What three atmospheric forces cause wind to blow?
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1) Pressure gradient ( H--> L)
2) Coriolis Force 3) Friction |
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The coriolis force is the deflection caused by a rotating object. The CF only affects wind _____, not _____.
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The coriolis force is the deflection caused by a rotating object. The CF only affects wind direction, not speed.
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The amount of wind deflection depends upon....
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The amount of wind deflection depends upon the rotation of the earth, the latitude and the object's speed. The CF is negligible at the equator and more effective at the poles.
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What is meant by wind friction?
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Friction is wind blowing across erth's surface and against of air molecules.
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Wind speed effects the ____, not the other way around.
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Wind speed effects the CF, not the other way around. The greater the wind speed, the greater the CF. Only large scale systems are affected by CF, hence, hurricanes/ tornados rotate counter-clockwise in N. Hemis.
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Northern hemisphere CF deflection is toward the ___, and southern hemisphere CF deflection is to the _____.
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Northern hemisphere CF deflection is toward the left, and southern hemisphere CF deflection is to the right.
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What are geostrophic winds?
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Geostrophic wind is a theoretical horizontal wind blowing in a straight path, parallel to the isobars (constant contour (height) lines) at a constant speed.
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Geostrophic winds are caused by...
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Geostrophic winds are caused by an exact balance of the pressure gradient force and the CF and it is found in the upper level wind flow.
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What is the pressure gradient?
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The acceleration of air due to pressure difference. It is usually responsible for accelerating a parcel of air from a high atmospheric pressure region to a low pressure region, resulting in wind. Pressure gradient force refers to the horizontal movement of air.
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What is the hyrdostatic balance?
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In the vertical, an exact balance between vertical the pressure gradient force and gravity. It allows earth's atmosphere to remain in place.
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What are the 3 common characteristics of wind?
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direction, speed, gustiness (gusts- an instanteous wind)
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Sustained wind speed is a __ minute average.
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Sustained wind speed is a 2 minute average.
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What is the conversion for wind speed?
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7 knots x 1.15 = mph
mph/1.15 = knots |
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What are 4 common wind instruments?
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1) wind vane (wind direction); 2) anemometer (wind speed); 3) wind sock; 4) aerovane (looks like an airplane; combines speed & direction)
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What are the scales of the atmosphere?
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microscale, mesoscale (biggest advancement in last 20 yrs), macroscale (synoptic scale & global scale)
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Who created the Single Cell Atmosphere Model?
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George Hadley
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What is the single cell atmosphere model?
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The model states that with higher pressure at the poles, sinking cold air flowed southward from the polar regions. Once it fot to the equator, after warming, with lower air pressure, it is lifted.
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What are the horse latitudes?
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They are subtropic latitudes between 30 and 35 degrees both north and south. This region, under a ridge of high pressure called the subtropical high, is an area which receives little precipitation and has variable winds mixed with calm.
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What are the Polar Easterlies?
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The dry, cold prevailing winds that blow from the high-pressure areas of the polar highs at the north and south poles towards low-pressure areas within the Westerlies at high latitudes.
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What are the Westerlies?
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The prevailing winds in the middle latitudes between 35 and 65 degrees latitude, blowing from the high pressure area in the horse latitudes towards the poles. These prevailing winds blow from the west to the east, and steer extratropical cyclones in this general manner.
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What are the Trade Winds?
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The prevailing pattern of easterly surface winds found in the tropics near the Earth's equator.
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What is the Intertropical Convergence Zone?
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The area encircling the earth near the Equator where winds originating in the northern and southern hemispheres come together.
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Average Global Surface Pressure (cool season)
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Cool Season: high pressure is over land, low pressure is over the water.
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Average Global Surface Pressure (warm season)
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Warm Season: low pressure is over land, high pressure is over the water.
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What are jet streams?
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Jet streams are mainly upper level steering winds.
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Polar Jet Streams
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Job is to get cold air out of the poles. They are found best at 300 mb in height or 30,000 ft ASL
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Subtropical Jet Stream
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Job is to get rid of hot air in equatorial regions. They are found best at 200 mb in height or 38,500 ft ASL
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Low Level Jet Streams
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Found best at 850-700 mb in height or 4,000-9,800 ft ASL. It is unusual b/c it is a lower level jet.
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What is an upwelling?
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An oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water.
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The southern oscillation that kills upwellings
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El Nino is the warmer than average equatorial Pacific Ocean wate temperature. Dec 1997 H --> L
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Thestronger the El Nino, the _____ the hurricane season (due to jet streams)
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Thestronger the El Nino, the quieter the hurricane season (due to jet streams)
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Nino H --> L
Nina L <-- H |
All are low's but L is the lowest of the lows and H is the highest of the lows
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Notable El Nino Event 1
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1982-83: strong event, $8 billion in damage
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Notable El Nino Event 2
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1986-87: weaker event, ended drought in SE USA
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Notable El Nino Event 3
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1991-92: strong event, severe TX flooding, 5yr drought ended in CA
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What are the 1st four Local Scale Winds?
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1) Land Sea Breezes
2) Mountain & Valley Breezes 3) Santa Ana Wind 4) Desert Wind |
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What are the 2nd four Local Scale Winds?
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1) Monsoons
2) Thermal Lows 3) Katabatic Winds 4) Chinook Wind |
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Land Sea Breeze: comes from the ___ during daytime ( ___shore flow) and from the ____ during the night ( ___shore flow).
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Land Sea Breeze: comes from the sea during daytime (onshore flow) and from the land during the night (offshore flow).
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Mountain Velley Breezes: during daytime, cooler air sinks in the _____ and rises on the _____. At night, cool air sinks on the _____ and rises in the _____.
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Mountain Velley Breezes: during daytime, cooler air sinks in the valley and rises on the slopes. At night, cool air sinks on the slopes and rises in the valley.
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Monsoon: a ______ wind shift. In South Asia, during the summer, there is a ___ over the land, so wind blows ______. During the winter, there is a ____ over the land, so the wind blows ______.
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Monsoon: a seasonal wind shift. In South Asia, during the summer, there is a low over the land, so wind blows landward. During the winter, there is a high over the land, so the wind blows seaward.
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What is a thermal low?
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A thermal low is a low pressure cirrculation created by changes in air temperature. *This results in summer monsoons over AZ.
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Katabatic Wind (______ Wind): a ____, ____slope wind (gravity) that can be very destructive; common in Greenland & Antarctica; referred to as a "mistral" in the Alps.
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Katabatic Wind (Glacial Wind): a cold, downslope wind (gravity) that can be very destructive; common in Greenland & Antarctica; referred to as a "mistral" in the Alps.
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Chinook Wind (_____ Wind): a ___, ____, downslope wind; moisture is left on westward side of slopes; eastern Rockies
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Chinook Wind (Snoweater Wind): a dry, warm, downslope wind; moisture is left on westward side of slopes; eastern Rockies
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Santa Ana Winds: very similar to ______ Winds; ___, ___, downslope _-N_ wind in CA. Most common in ___ months (esp in ___)
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Santa Ana Winds: very similar to Chinook Winds; warm, dry, downslope E-NE wind in CA. Most common in fall months (esp in Oct)
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Desert Wind: Haboobs (a type of intense sandstorm) in North Africa & India --> T-stroms --> Dust storms --> Dust devils
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Other Local Wind terms: Eddy- A current moving contrary to the direction of the main current, especially in a circular motion.
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Other Local Wind terms: Wind Shear- a rapid change in wind _____ and/or ____ in a small area in the atmosphere (causes: ___, ____, ___)
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Wind Shear- a rapid change in wind direction and/or speed in a small area in the atmosphere (causes: cold fronts, hurricanes, t-storms)
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What is an air mass?
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It is a body of air covering a relatively wide area, exhibiting approximately uniform properties through any horizontal section.
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N. Amer. air masses:
1) A or cA 2) cP 3) mP |
1) A or cA: continental arctic; 2) cP: continental polar --> lake effect snows; 3) mP: maritime polar, originate over Atlantic/Pacific.
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N. Amer. air masses:
4) mT 5) cT |
4) mT: maritime tropical (our air mass, which is impt for t-storm development).
5) cT: continental tropical |
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1) What cause cyclogenesis?
2) How do cycloes (anticones) travel? |
1) Upper air conditions
2) upper level winds low pressure cyclones are less favored when upper level winds are divergent |
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What are two types of frontal lows?
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tropical low = warm core low
extratropical low = cold core low |
