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Show Pressure ! In The j Heather J What causes the pressure in a high pressure area? g Likewise, in a low pressure . area? Where does the barometric pressure come 4 from? 4 THE HIGH and low pres- f sure we so often hear about . these days merely refers to the height of the layer of 4 gases above the earth's sur- g face at a given point or in a . given area. In other words, if ' you are in a high pressure 4 area, the layer of gases above you is very high. . On the contrary, if you are in a low pressure area, the layer of gases above you is g very low. The main function T of a barometer is simply to ' measure the weight of the gas above you and it does this by g recording an accurate measurement of the weight, ' or pressure, of the gas press- ( ing down on the surface of the earth, which is the weather. ' WE TALK of inches of ' mercury because the long-ac- cepted official instrument for measuring the weight (or pressure) or the layer of gas I above us has been a mercury ( barometer in the form of a . column of mercury, measured in Inches. i |