Atmospheric Pressure and Winds — Flashcards

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Atmospheric pressure is the pressure exerted by the atmosphere on the Earth’s surface. It is the weight of a column of air at a given place and time. Under normal sea-level conditions, it equals 76 cm…

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An isobar is an imaginary line drawn through places having equal atmospheric pressure reduced to sea level. Isobars help show the distribution of pressure on a map. Close spacing means a strong pressu…

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Pressure gradient is the rate of decrease in pressure per unit distance in the direction in which the pressure decreases. A strong pressure gradient produces faster winds, while a weak pressure gradie…

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When air is heated, it expands, becomes lighter, and exerts less pressure. When air cools, it contracts, becomes denser, and exerts more pressure. So, higher temperature means lower pressure, and lowe…

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Atmospheric pressure decreases with height because the weight of the air column above becomes smaller at higher altitudes. About half of atmospheric pressure is confined to the first 6 km of height. O…

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Dry air is heavier than moist air because water vapour is lighter than the main gases of air. When the amount of water vapour increases, air becomes less dense and pressure decreases. This is one reas…

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The gravitational pull of the Earth helps air stay close to the surface and exert pressure. Since gravitational pull decreases with distance from the Earth’s centre, places nearer the centre experienc…

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Earth’s rotation creates centrifugal force, which tends to throw air outward. This effect is strongest at the equator, so pressure is lowest there. Rotation also influences the movement and direction …