GEG-1 Lecture Notes - Lecture 12: Arctic Air, Westerlies, Polar Front
Document Summary
An air mass is a large volume of air with the climate conditions of the area where it is formed. An air mass originating in a continental climate will be dry because it is far from a large body of water. Landforms affect the movement of air masses: one side of a mountain has warm, rainy weather, whereas the other side has cold, dry weather. Air has weight, and this weight is called air pressure. The average pressure of air at sea level is 101. 3 kpa. There is less air on top of a mountain than at sea level. Therefore, air pressure is less at a high elevation than at a low one. Differences in air pressure are created when the earth is heated to different temperatures. Warmed air rising above the heated ground creates an area of low pressure. When the rising air has cooled, it falls toward the earth and creates an area of high pressure.
