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Weather & Climate
Test 2
45
Geography
Undergraduate 1
10/06/2010

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Term
Air Pressure
Definition
The force exerted per unit area, or the force exerted on a surface by the air.
Term
Characteristics of Air Pressure
Definition
1) It can vary both spatially and temporally
2) The avg. surface pressure is 1013 mb.
3) It is shown on a map as lines of equal pressure or H (high) & L (low)
Term
Pressure Gradient Force (PGF)
Definition
A force that arises from spatial variation in pressure, or the difference in air pressure from one point on the Earth's surface to another.
Term
Winds flow from areas of _____ pressure to areas of _____ pressure.
Definition
HIGH, LOW
Term
_____ _______ & the PGF determine wind direction & strength or speed
Definition
Air Pressure
Term
Differential Heating
Definition
the motive force behind land breezes and sea breezes (or, in the case of larger lakes, lake breezes), also known as on- or off-shore winds. Land is a rapid absorber/radiator of heat, whereas water absorbs heat more slowly but also releases it over a greater period of time
Term
Coriolis Effect
Definition
A deflective force arising from Earth's rotation that is used to account for motions measured relative to the surface, or the apparent deflection in path or movement of an object moving over the Earth's surface due to Earth's rotation.
Term
Characteristics of Coriolis Effect
Definition
1) It's strongest at the poles & zero at the equator
2) An object's speed will alter the amount of deflection, increase speed = increase deflection
3) It alters direction, but NOT the speed of an object
4) It affects not only wind, but ocean currents, flight paths of planes and missiles, etc.
Term
Types of Wind
Definition
Geostrophic & Surface
Term
Geostrophic Winds
Definition
Upper level winds, > 1-2 km's above the surface.
Term
Characteristics of Geostrophic Winds
Definition
1) They're affected by PGF & CF
2) They blow parallel to isobars with little or no friction
Term
Main Patterns of Geostrophic Winds
Definition
1) Zonal Flow = a more 'flattened' air flow with primarily an east-west flow
2) Meridional Flow = a more north-south or curved flow with distinct ridges (High Pressure) and troughs (Low Pressure)
Term
Jet Stream
Definition
A meandering "river" of air usually 9 to 12 km above sea level, with high wind speeds. They are highly turbulent and their speeds and location will vary considerably.
Term
Rossby Waves
Definition
Waves in the mid-latitude westerlies having wavelengths on the order of thousands of km's. They often circle the planet, forming a pattern of ridges and troughs.
Term
Surface Winds
Definition
Winds below 1-2 km that are in contact with the Earth's surface.
Term
Characteristic of Surface Winds
Definition
1) They're affected by PGF, CF, and Friction
Term
Low Pressure Cells
Definition
* have cyclonic or counterclockwise flow in the NH
* have anticyclonic or clockwise flow in the SH
Term
High Pressure Cells
Definition
* have anticyclonic or clockwise flow in the NH
* have cyclonic or counterclockwise flow in the SH
Term
Wind Measurements
Definition
Direction & speed
Term
Direction
Definition
N, S, E, W, NE, SE, NW, SW
* Winds are always named for the direction they are coming from
Term
Speed
Definition
* Usually recorded by an anemometer in mph or kph
Term
Measuring Scales for Wind
Definition
Macroscale, Mesoscale, Microscale, & Planetary Scale
Term
Planetary Scale Winds
Definition
1) Trade Winds - in the tropics; NH has the NE tradewind, SH has the SE tradewind
2) Westerlies - Subtropics; NH & SH
3) Easterlies - Subpolar; NH & SH; High pressure
Term
Types of Local Winds
Definition
1) Land/Sea Breezes
2) Valley/Mountain Breezes
3) Chinook
4) Katabatic
Term
Land/Sea Breezes
Definition
Occurs in coastal areas; dependent on position of local High & Low pressure cells
* High pressure over the land = Land breeze
* High pressure over the sea = Sea breeze
Term
Valley/Mountain Breezes
Definition
Warm wind going up the mountain during the day and cool wind coming down at night
Term
Chinook Wind
Definition
Warm, dry wind coming off (down) the mountains. Also known as the Santa Ana winds in California.
Term
Katabatic Wind
Definition
A flow of dense, cold air downslope under the influence of gravity. Primarily found over large ice sheets, such as those found in Greenland and Antarctica.
Term
Idealized Pattern of Pressure
Definition
* Changes temporally & spatially
* It's altered from the idealized pattern by land masses & seasonality, differential heating
Term
Low Belts
Definition
Areas of uplift with convergence at the surface; usually unstable
Examples: ITCZ & Subtropical Lows (SPL)
Term
High Belts
Definition
Areas of subsidence and divergence at the surface; usually stable
Examples: STH, Polar High (PH)
Term
Hydrologic Cycle
Definition
the continuous movement of water from the Earth's surface to the atmosphere and back to the surface, then to the atmosphere..
Term
Hydrologic Cycle's Basic Processes
Definition
Evaporation & Transpiration (Evapotranspiration), Condensation, Precipitation, Runoff
Term
Difference Between Transpiration and Evapotranspiration
Definition
* Transpiration - the water absorbed by vegetation & then released to the atmosphere
*Evapotranspiration - the combined amount of water lose by evaporation & transpiration
Term
States of Water (Matter)
Definition
Solid, liquid, gas
Term
Humidity
Definition
The amount of water vapor in the air that can be measured in different ways
Term
Specific Humidity
Definition
* g of H2Ov (water vapor) / kg of air
Term
Absolute Humidity
Definition
g of H2Ov / m3 of air
Term
Relative Humidity
Definition
* Actual H2Ov content / H2Ov capacity x 100
* When RH = 100%, the air is saturated
* This is controlled by water vapor content & the air's capacity, which is controlled by Temp.
Term
Partial Pressure
Definition
Each component of the atmosphere makes up a part of the total air pressure
Term
Water Vapor Pressure
Definition
the portion of the air pressure which is made up by water vapor
Term
Saturation
Definition
* When the air is holding all the water vapor it can
* Warmer air can hold more water vapor
* Saturation vapor pressure increases with increasing T
Term
Dew Point
Definition
The T to which air must be cooled to become saturated
Term
Dew Point Temperature
Definition
* The T at which saturation will occur, given sufficient cooling
* It is an indication of the moisture level in the air
* It is controlled by vapor pressure, not by air T
Term
How to change the RH
Definition
1) By adding or subtracting water vapor
2) lowering or raising the T
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