Chapter 19: Air Pressure and Wind – Flashcards

the force exerted by the weight of a column of air above given point

an instrument that measures atmospheric pressure

the amount of pressure change occurring over a given distance

the apparent deflective force of Earth's rotation on all free-moving objects, including the atmosphere and oceans; Deflection is to the right in the Northern Hemisphere and to the left in the the Southern Hemisphere

swift (120-240 kilometers per hour), high-altitude winds

a low-pressure center characterized by a counterclockwise flow of air in the Northern Hemisphere

a high-pressure center characterized by clockwise flow of air in the Northern Hemisphere

two belts of winds that blow almost constantly from easterly directions and are located on the north and south sides of the subtropical highs

the dominant west-to-east motion of the atmosphere that characterizes the regions on the poleward side of the subtropical highs

in the global pattern of prevailing winds, winds that blow from polar origin from warm air masses of tropical origin

the stormy frontal zone separating cold air masses of polar origin from warm air masses of tropical origin

seasonal reversal of wind direction associated with large continents, especially Asia; In winter, the wind blows from land to sea. In summer, the wind blows from sea to land

a wind that consistently blows from one direction more than from another

an instrument used determine wind speed

the name given to the periodic warming of the ocean that occurs in the central and eastern Pacific; A major El Niño episode can cause extreme weather in many parts of the world

The force exerted by the weight of a column of air above a given point

A barometer is an instrument that measures atmospheric pressure.

When air pressure increases, the mercury in the tube rises. When air pressure decreases, so does the height of the mercury column. With some improvements, the mercury barometer is still the standard instrument used today for measuring air pressure.

In cyclones, the pressure decreases from the outer isobars toward the center.

In anticyclones, just the opposite is the case--the values of the isobars increase from the outside toward the center.

When the pressure gradient and the Coriolis effect are applied to pressure centers in the Northern Hemisphere, winds blow counterclockwise around a low. Around a high, they blow clockwise.

Whenever air converges (or comes together) horizontally, it must increase in height to allow for the decreased area it now occupies.

In either, friction causes net flow of air inward around a cyclone and a net flow of air outward around an anticyclone.

Small-scale winds produced by a locally generated pressure gradient are known as local winds. The local winds are caused either by topographic effects or by variations in surface composition--land and water--in the immediate area.

In the United States, the westerlies consistently move weather from west to east across the continent.

The name given to the periodic warming of the ocean that occurs in the central and eastern Pacific; A major El Niño episode can cause extreme weather in many parts of the world.

At irregular intervals of three to seven years, these warm countercurrents become unusually strong and replace normally cold offshore waters with warm equatorial waters.

There are weather effects, economical effects, and agricultural effects. El Niño affected the fishing industry and cotton/other agriculture and produces more weather.

An episode of strong trade winds and usually low sea-surface temperatures the central and eastern Pacific.

Researchers have come to recognize that when surface temperatures in the eastern Pacific are colder than average, a La Niña event is triggered that has a distinctive set of weather patterns.

Air pressure is exerted in all directions--down, up, and sideways. The air pressure pushing down on an object exactly balances the air pressure pushing up on the object.

The unequal heating of Earth's surface generates pressure differences.

Solar radiation is the ultimate energy source for most wind.

Swift (120-240 kilometers per hour), high-altitude winds

Three factors combine to control wind: pressure differences, the Coriolis effect, and friction.

Closely spaced isobars indicate a steep pressure gradient and high winds. Widely spaced isobars indicate a weak pressure gradient and light winds.

A low-pressure center characterized by a counterclockwise flow of air in the Northern Hemisphere.

A high-pressure center characterized by a clockwise flow of air in the Northern Hemisphere.

Seasonal reversal of wind direction associated with large continents, especially Asia; In winter, the wind blows from land to sea. In summer, the wind blows from sea to land.

Two belts of winds that blow almost constantly from easterly directions and are located on the north and south sides of the subtropical highs.

A sea breeze then develops because cooler air over the water at high0pressure moves toward the warmer land and low-pressure air. The breeze starts developing shortly before noon and generally reaches tis greatest intensity during the mid-to late afternoon. These relatively cool winds can be a moderating influence on afternoon temperatures in coastal areas.

A wind that consistently blows from one direction more than form another.

Cyclones typically bring rain, thunderstorms, and strong winds.

Anticyclones typically bring calm, sunny weather.

In the Northern hemisphere, the winds associated with a low pressure system (cyclone) blow counterclockwise and toward the center. In the Southern Hemisphere, the winds associated with a high pressure system (anticyclone) blow clockwise and toward the center.