Air pressure is the amount of pressure the weight of air exerts on a specific point. In terms of weather, air pressure is measured in millibars, hectopascals or inches of mercury. For items such as tires and other inflat... More »

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Air pressure is caused by the weight of the air pressing down on the Earth, the ocean and the air below. Air pressure is also known as atmospheric pressure and barometric pressure. More »

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A barometer is a device used to measure air pressure, or atmospheric pressure. The first kind of barometer invented was the mercury barometer. The other type, the aneroid, is a digital barometer. More »

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Air pressure is caused by the weight of the air pressing down on the Earth, the ocean and the air below. Air pressure is also known as atmospheric pressure and barometric pressure. More »

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Air pressure, the force exerted on a mass by the weight of air particles, is measured in either inches of mercury or in millibars, represented by inHg and mb, respectively. One standard atmosphere, represented by the sym... More »

Air pressure changes with altitude because of issues related to gravity. Molecules have more weight the closer they are to the Earth and more of them move to lower elevations as a result; this causes increased pressure b... More »

Air pressure decreases with altitude. The combined weight of air molecules at increasing altitude decreases. Air pressure is greatest at the Earth's surface, because the surface air molecules bear the combined weight of ... More »