Atmospheric pressure is a force in an area pushed against a surface by the weight of air in Earth's atmosphere. The earth is covered in a layer of air. However, this layer is not distributed evenly around the globe. At different times, the layer of air is thicker in some places than in others. Where the layer of air is thicker, there is more air. Since there is more air, there is a higher pressure in that spot. Where the layer of air is thinner, there is a lower atmospheric pressure. The higher the elevation, the thinner the air is. Mercury barometers can be used to measure atmospheric pressure. There is the same atmospheric pressure from all directions.
Atmospheric pressure is measured in hPa. The higher the place is, the lower the atmospheric pressure is there. This is because high places do not have as much air as low places because gravity does not hold it down as strongly, so the atmospheric pressure is less.
- "atmospheric pressure -- Britannica Online Encyclopedia". britannica.com. http://www.britannica.com/EBchecked/topic/41486/atmospheric-pressure. Retrieved 11 August 2010.
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- "Experiment of soda cans being crushed using atmospheric pressure". teachertube.com. http://www.teachertube.com/viewVideo.php?video_id=62613. Retrieved 11 August 2010.