Atmospheric Pressure (OCR GCSE Physics A (Gateway Science Suite)): Revision Notes
📚 Revision Notes
5.5.2 Atmospheric Pressure
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There is a thin layer of air around the earth called the atmosphere. The atmosphere gets less dense as the height above earth (altitude) increases.
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Air molecules collide with the surface of the atmosphere, creating atmospheric pressure. This atmospheric pressure decreases with increasing altitude. This is because as the altitude increases, the atmosphere is less dense. Therefore there are less particles to collide with the surface, so the pressure decreases.
Also, as the height increases, there is less air particles on top of the surface. This means less weight of air on top of the surface contributing to the pressure. So this contribution to the pressure also decreases with altitude.