GEOG220 Lecture Notes - Lecture 19: Tropopause
28 Apr 2016
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Document Summary
At upper levels of the atmosphere there i no friction so you get. Geostrophic balance and geostrophic winds (blow parallel to height lines) Near the earth"s surface you have to take friction into account, so you can"t get geostrophic winds. Instead there"s a balance between pgf cf and. If the wind is weaker, the cf is weaker. If the cf is weaker, it can"t balance the pgf and the winds will cross the isobars in the direction of the pgf. The pgf will ultimately be balanced by the sum of the friction and cf. At the surface,winds cross the isobars towards the low pressure and away from high pressure. The angel at which the winds cross the isobars depends upon the roughness of the earth"s surface. The rougher the surface, the slower the wind speed for a given pgf and the larger the crossing angle. We know that air near the earth"s surface crosses the isobars toward low pressure.
