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Unformatted text preview: altitude there is less air pressing downward and air pressure is less 8 Effects of air movement Basic Properties of Air: What happens when air rises to higher altitudes? 1. It expands It expands because pressure is lower 2. It Cools It cools because expansion leads to cooling (PV = nRT) Example: Air coming out of a tire is cool 9 Effects of air movement Basic Properties of Air: 3. It may rain. Cold air can hold less water than warm air: So water (in rising air) may condense and fall. 1+2+3. Rising air rain or snow: When warm air rises, it expands, cools off and can not hold as much water vapor…so it rains/ snows 10 Effects of air movement
Example of how air movement affects climate: Rain shadow
Wet green side Very dry brown side Basic Properties of Air: 11 Rain shadow
Air rises, expands and cools. Result: rain on windward side Moist air Wind Evaporation Dryer air blows to leeward side, sinks and warms up. Result: dry warm area, called a rain shadow. windward side: Wet Leeward side Dry
12 Rain shadow 13 Field Trip Big IslandHawaii 14 15 16 17 18 Class question Which side of the island gets 128 inches, and which side gets 10 inches, of rain a year? Why? Explain the large difference. Important: The wind comes off the Pacific Ocean from the East 19 20 Example 2: Atmospheric convection (mixing) Effects of air movement
2) Rising air expands, cools, relative humidity rises until condensation of water vapour occurs above condensation level. Basic Properties of Air: Condensation level 1) Air warms by contact with warm ground...
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- Spring '08