relative humidity

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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. - PowerPoint PPT Presentation

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  • Relative HumidityIs 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 -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.Sling Psychrometer

  • Hair Hygrometer -Hair changes length depending on humidity - bad hair days!

  • Cold is airs kryptoniteWarm air can hold more moisture.Cold air holds less moisture.So, cooling air reduces the airs 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?

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