Geography 2131A/B Lecture Notes - Lecture 3: Coriolis Force, Northern Hemisphere, Atmospheric Pressure
30 Mar 2017
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Document Summary
Wind - movement of air relative to earth"s surface. The speed and direction of the wind is caused by 4 main forces: gravitational force o o o. The atmosphere (i. e. all of the air molecules) is held close to the earth by gravity: mass decreased with altitude due to fewer air molecules, atmospheric pressure. A difference between the surface pressure at two locations. Larger difference = faster movement within gradient. Apparent deflective force due to a spinning earth. Strongest at the poles and over large distances. Northern hemisphere deflected to the right, southern hemisphere to the left. Lands to the right, doesn"t matter if you throw towards the north or south. Air molecules near the earth"s surface can be slowed down by "rough" surfaces. Geostrophic winds: wind flowing in a relatively straight line due to balance of pressure-gradient and coriolis forces o o. Common in the "free" atmosphere - where friction doesn"t influence the wind.
