GEOB 102 Lecture Notes - Lecture 9: Atmospheric Circulation, Coriolis Force, Pressure Gradient

• School: UBC
• Department: Geographical Biogeosciences
• Course: GEOB 102
• Professor: Simon Donner

Document Summary

Atmospheric pressure is the force produced by the weight of a column of air above a unit area of surface. Gravity pulls air molecules towards the earth"s surface. Fluids like air and water move from areas of higher pressure to lower pressure. A barometer is used to measure air pressure. Pressure normally ranges from 1050 mb to 950 mb (105 to 95 kpa) The lowest pressures occur at the centre of tropical storms. Wind- horizontal motion across the earth"s surface- is created by gradients in air pressure (or air density) The greater the pressure difference or gradient, the stronger the winds. Any parcel of air near the surface is subjected to four forces: Coriolis force" (fc) acts at a right angle to the direction of motion. Frictional force (ff) acts opposite to the direction of motions; proportional to wind speed. Areas of high and low pressure occur because of uneven heating of the earth"s surface.