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Details Title: Earth Science - Chapter 18 Description: 18 - AIR Pressure and WIND Total Flash Cards: 34 Created: 04/24/2006 12:20:56	To study from this set of flash cards, or to create your own your own study flash cards, register HERE. If you are already a registered user, CLICK HERE.
Cards Term Air pressure Definition Force exerted by the weight of overlying air Decreases with altitude millibars, pascals, inches of mercury Term how air pressure is measured Definition mercury barometer aneroid barometer - without liquid barograph - continuous record over time Term Factors affecting wind Definition pressure-gradient force coriolis effect friction Wind is the result of horizontal differences in air pressure Wind balances inequalities of air pressure! If earth not rotate, winds flow in straight lines Term pressure-gradient force Definition amount of pressure change over a given distance air pressure on a weather map is indicated by isobars driving force of wind has magnitude and direction = pressure / horizontal distance (isobars) Term coriolis effect Definition Moving objects are deflected to the right of the wind in the northern hemisphere, and to the left in the southern hemisphere directed at right angles to the direction of the wind increases at higher wind speeds strongest at poles Term Friction with the Earth’s Surface Definition slow air movement, alters wind direction Significant only within a few kilometers of the surface Above friction layer, the pressure-gradient and Coriolis force work together to direct upper-level winds. Term Geostrophic winds Definition Upper-level winds that flow parallel to the isobars Reflect a balance between the Pressure-Gradient Force and the Coriolis Effect Due to lack of friction, travel at higher speeds than surface winds Term isobars Definition lines of constant air pressure Term jet streams Definition Most prominent feature of upper-level winds Fast-moving “rivers of air” hundreds to thousands of kilometers in length EAST - WEST direction Term upper level vs. surface level winds Definition upper level - surface level - Affected by friction, reduces the Coriolis Effect Pressure-gradient force is not affected by friction winds move across isobars at an angle from high to low pressure areas. Roughness of surface terrain has an affect Term lows or cyclones Definition centers of low pressure (ascending air masses) pressure increases from center outward friction causes a net inflow of air around a cyclone (convergence) airflow counterclockwise Term highs or anticyclones Definition centers of high pressure (descending air masses) pressure decreases from center outward friction causes a net outflow of air around an anticyclone (divergence) airflow clockwise Term highs Definition winds move outward and in a clockwise direction in the northern hemisphere outward and counterclockwise in the southern hemisphere because air warms adiabatically as it is compressed and descneds, few clouds and no rain is associated with highs Term lows Definition winds move inward and in a counterclockwise direction in the northern hemisphere inward and clockwise in the southern hemisphere because air cools adiabatically as it rises, lows are associated with cloudy conditions and precipitation Term convergence vs. divergence Definition convergence - sinking motion, high divergence - upward motion, low Term wind Definition the result of horizontal differences in air pressure air flows from high to low pressure Term affect of continents Definition large seasonal temperature changes disrupt the idealized global circulation patterns winter - cold landmasses develop a seasonal high pressure system wind blows off land summer - warm landmasses develop a seasonal low pressure system wind blows onto the land Term local winds Definition small-scale winds produced by locally generated pressure-gradient force Term sea breezes Definition cooler air over the ocean (higher prpessure) move towards warmer land (lower pressure) strongest in afternoon Term land breezes Definition land cools more quickly than water cooler air over land (higher pressure) moves towarn warmer pressure water Term valley breezes Definition clouds form over peak, air moves over valley, cools down at nighttime nighttime reversed, cold air down mountain Term mountain breezes Definition mountain slopes heat faster than air at same elevation Term chinook winds Definition warm, dry winds on the eastern slopes of the rocky mountains formed by descending air on the leeward side of a mountain and warmed by compression Term santa ana winds Definition produced by high pressure centered over great basin most common during winter compression causes heating and relative dying. or drying. results in majore fire hazard during late summer or fall Term ~ el nino Definition name given to periodic warming of central and eastern pacific ocean associated with periods when a weakened pressure gradient causes the trade winds to diminish can trigger worldwide change in weather Term General circulation of the atmosphere Definition winds are affected by the coriolis effect uneeven distribution between land and water causes displacement curved wind patterns named in direction they are coming from position of jet streams associated with wind zones Term doldrums Definition area of calm The trade winds coming from the south and the north meet near the equator produce general upward winds as they are heated, so there are no steady surface winds Term barometric tendency Definition change of atmospheric temperature lows are usually accompanied by storms while highs generally signal fair weather Term prevailing westerlies Definition between thirty and sixty degrees latitude winds that move toward the poles appear to curve to the east. Term trade winds Definition The air movements toward the equator warm, steady breezes The Coriolis Effect makes the trade winds appear to be curving to the west Term prevailing easterlies Definition weather systems move from east to west in the tropics Term horse latitudes Definition winds are light and the weather is hot and dry, mostly over ocean associated with the subtropical anticyclone and the large-scale descent of air from high-altitude currents moving toward the poles RIP horses. Term southern oscillation Definition oscillation in the surface pressure (atmospheric mass) between the southeastern tropical Pacific and the Australian-Indonesian regions When the waters of the eastern Pacific are abnormally warm (an El Niño event) sea level pressure drops in the eastern Pacific and rises in the west The reduction in the pressure gradient is accompanied by a weakening of the low-latitude easterly trades. Term coriolis force Definition Once air has been set in motion by the pressure gradient force, it undergoes an apparent deflection from its pathh result of the earth's rotation amount of deflection directly related to speed and latitude winds blowing closer to the poles will be deflected more than winds at the same speed closer to the equator