What exactly is high pressure and low pressure in weather ?
I am sorry but I think Paul has got it wrong: A low pressure is generated by warm air that rises and not the opposite. But first, what is a low and high pressure? Well, it is a pressure that is, at sea level, higher or lower than the average on earth, which is 1013,25 hPa or 29.9 Hg In, as it is measured in the US. When the heat of the sun warms up the earth or sea, a thin layer or air right above it, rises and that lowers the pressure. Therefore, the equator, the warmest place on earth, is a region of low pressures. The two poles, on the other hand, are regions of high pressure because the cold air sinks there. If it wasn’t for the Coriolis force that results from the earth’s rotation, the air would probably move aloft from equator to poles, and the other way along the surface. But the Coriolis force bends any large system movement to the right hand in the northern hemisphere and what rises at the equator, comes down as two belts of high pressures at roughly latitudes 30 N and 30 S. B
