VIEWS: 5 PAGES: 7 POSTED ON: 8/19/2012
Relative Humidity Is how much moisture a given mass of air is holding compared to how much water that air is capable of holding expressed as a percent. What % full? What would happen to that % if the same water were in a smaller glass? How to measure humidity - Sling Psychrometer • Remember - evaporation cools things (sweat, misters in outdoor cafes, etc.) • Evaporation goes faster in dry air. • The drier the air - the greater the difference between wet and dry- bulb temperatures. Hair Hygrometer - • Hair changes length depending on humidity - “bad hair days”! Cold is air’s kryptonite • Warm air can hold more moisture. • Cold air holds less moisture. • So, cooling air reduces the air’s ability to hold moisture, and if that air was holding a lot of moisture, it may drop moisture (condensation). • What happens to RH if you warm the air? Dew point - • The temperature that you have to cool air to in order to make the air drop its moisture is the dew point. • RH = 100% at DP. • Is dew point high or low on a dry day? If you cool air to its dew point, condensation happens. • If you breathe on cold glass, moisture from your breath ____________ on the glass. • If you cool air up in the sky to its dew point, water vapor condenses into ___________. • If you cool air near ground level to its dew point, ______ forms. • On cool mornings, _____ forms on cool grass. • If the dew point is below freezing (32f or 0c) and the air gets that cold , _______ would form on grass instead of dew. Why do clouds have flat bottoms?
Pages to are hidden for
"Relative Humidity"Please download to view full document