EAPS 10200 Lecture Notes - Lecture 10: Coriolis Force, Pressure-Gradient Force, Barometer
8 Oct 2017
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Measuring air pressure: torricelli invented the mercury barometer in 1643, a glass tube, open at one end, is first filled with mercury and then inverted vertically in a dish of mercury. Pressure gradient force and wind: from earlier discussions we know that warm air rises and cold air sinks resulting in vertical movement of air. At the same time there is a build up of air above the warm air and on the surface at the cold air. On the surface air will move from more air to less air and likewise above the surface. This is called the pressure gradient force and creates wind. Isobars are lines of constant pressure either on the surface or above the surface. Air always flows from areas of high pressure to areas of lower pressure. If the isobars are widely spaced than the pressure gradient is weaker resulting in weak winds.
