GEOG 2110L Chapter Notes -Meridional Flow, Zonal Flow, Coriolis Force
17 Mar 2014
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*** air pressure: the weight of the air pushing down on a surface. ** avg. surface pressure = 1013 mb, 29. 92 inches of hg (mercury) ** shown on a map as lines of equal pressure or isobars. * high or heavy pressure cells ----- h. ** pressure gradient force (pgf): difference in air pressure between two places, horizontally. ** initiates horizontal air flow or advection = wind. *** air pressure & the pgf determine wind direction & wind strength or speed. ** steep gradient == strong pgf == strong (fast) winds. ** gentle gradient == weak pgf == light (slow) winds. * winds flow from areas of high pressures to areas of low pressure. *** these diferences in pressure are set-up by differences in temperature created by differential heating. energy imbalance (cid:0) t difference (cid:0) pressure difference (cid:0) wind. * objects move independent of the earth"s rotation. * the whole earth"s surface does not spin at the same rotational velocity.
