A&O SCI 1 Lecture Notes - Lecture 4: Precipitable Water, Atmospheric Circulation, Relative Humidity
4 Oct 2016
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Document Summary
Air temperature taken at a few meters above the surface. There are bands of high temperatures mostly along the tropics. Heating changes with seasons, drives seasonality and circulation. A rising motion is balanced with a sinking motion. There are convection cells called convective overturning. Convective overturning is this loop of heat rising. Air becomes cooler which reduces its capacity to hold water. This causes it to become oversaturated and the water condenses into droplets. We can express the vapor content as a mixing ratio, the mass of water vapor compared to the total mass of air (g/kg) The relationship between the mixing ration of water vapor at saturation and temperature is known as the clausius-clapeyron relation. We can estimate saturation with the temperature. As saturation increases and temperature of the vapor reduces more and more it ends up becoming water and the saturation reduces through precipitation. Completely saturated air has a relative humidity of 100%
