Patterns of Circulation in the Atmosphere

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Atmospheric circulation Noun

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[at-muh-sfer-ik sur-kyuh-ley-shuhn]

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Atmospheric circulation

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The large-scale movement of air by which thermal energy is distributed on the surface of the Earth.

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Example: This diagram shows how Earth's rotation and uneven heating create large, predictable wind patterns, a key part of global atmospheric circulation.

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Convection cell Noun

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[kuhn-vek-shuhn sel]

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Convection cell

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A self-contained circulatory system in a fluid, like air, created by density differences from heating and cooling.

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Example: This diagram shows a convection cell in action as a sea breeze. Warm air over the land rises, and cooler air from the sea moves in to replace it, creating a circular wind pattern.

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Coriolis effect Noun

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[kawr-ee-oh-lis ih-fekt]

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Coriolis effect

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The apparent deflection of moving objects, like wind, caused by Earth's rotation, turning them right in the Northern Hemisphere.

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Example: Because the Earth rotates, moving air is deflected, causing storms to spin counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

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Hadley cell Noun

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[had-lee sel]

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Hadley cell

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A large-scale atmospheric convection cell where air rises at the equator and sinks at medium latitudes around 30°.

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Example: This diagram shows how warm, moist air rises at the equator, then cools and sinks as dry air around 30° latitude, creating a large circular pattern.

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Ferrel cell Noun

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[fer-uhl sel]

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Ferrel cell

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The atmospheric circulation cell in the mid-latitudes, characterized by sinking air near 30° and rising air closer to the poles.

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Example: This diagram shows the Ferrel cell is a pattern of air circulation in the middle latitudes, located between the Polar and Hadley cells.

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Polar cell Noun

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[poh-ler sel]

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Polar cell

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The smallest atmospheric circulation cell where cold, sinking polar air flows from the poles toward about 60-70° latitude.

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Example: This diagram shows the Polar Cell as a circulation of air near the Earth's poles, located between 60 and 90 degrees latitude.

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Trade winds Noun

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[treyd windz]

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Trade winds

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Steady east-to-west prevailing winds that flow in the Earth's equatorial region between approximately 0° and 30° latitude.

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Example: This diagram shows the Earth's major wind patterns. The Trade Winds are surface winds that consistently blow from the subtropics towards the warm equator.

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Westerlies Noun

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[wes-ter-leez]

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Westerlies

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Prevailing winds blowing from west to east in the middle latitudes, between 30° and 60° latitude, steering storms.

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Example: This diagram shows the Earth's main wind patterns, locating the westerlies between 30° and 60° latitude, where winds blow from the west.

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Polar easterlies Noun

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[poh-ler ee-ster-leez]

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Polar easterlies

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Cold, dry prevailing winds that blow from high-pressure polar regions toward lower pressure areas in the high latitudes.

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Example: This diagram shows Earth's global wind patterns, with arrows pointing to the polar easterlies as cold air moving away from the North Pole.

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Jet stream Noun

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[jet streem]

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Jet stream

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Narrow, fast-flowing bands of wind in the upper atmosphere that guide storm tracks and mark boundaries between air masses.

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Example: This image shows the jet stream as a fast-moving river of air that separates colder northern air from warmer southern air.