What is the pressure related movement of air called?
1 Air pressure is the weight of the atmosphere pressing down on the earth. 2  It is measured by a barometer in units called millibars. 3  Most barometers use mercury in a glass column, like a thermometer, to measure the change in air pressure.ir Pressure and Humidity. 1  Air pressure is the weight of the atmosphere pressing down on the earth. 2  It is measured by a barometer in units called millibars.