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24 Cards in this Set
- Front
- Back
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Referred to as the amount of water vapor in the air |
Humidity |
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Process bh which liquid water is converted into vapor |
Vaporization/Evaporization |
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Process of water molecules leaving a snow/ice surface in the same manner as they leave liquid |
Sublimation |
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Process by which vapor changes to liquid or solid state |
Condensation |
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Amount of heat absorbed by a unit mass of a substance, without change in temperature, while passing from liquid to vapor state |
Latent heat of vaporization |
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Amount of heat released by a unit mass of a substance while changing from vapor to liquid state |
Latent heat of condensation |
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Amount of heat required to convert one gram of ice to liquid water at the same temperature |
Latent heat of fusion |
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Amount of heat required to convert one gram of ice into vapor at the same temperature without passing through the intermediate liquid state |
Latent heat of sublimation |
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Atmospheric moisture can be expressed in several ways |
1. Absolute humidity 2. Mixing ratio 3. Specific humidity 4. Vapor pressure 5. Relative humidity 6. Dewpoint temperature 7. Wet bulb temperature |
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Partial pressure exerted by water vapor in the atmosphere |
Vapor pressure |
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Formula for vapor pressure |
P = Pd + ea |
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Teten's formula |
es = 0.6108e^[17.27T/T+237.3] |
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Vapor pressure deficit formula |
VPD = es - ea |
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Relative humidity formula |
RH = ea/es * 100 |
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Temperature to which air must be cooled at constant pressure to become saturared at its current vapor content |
Dewpoint temperature |
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Tdp formula |
Tdp = 237.3 ln(ea/0.6108) ---------------------------- 17.27 - ln(ea/0.6108) |
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Temperature to which the latent heat of vaporization will cool the ambient air |
Wet bulb temperature |
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Twb formula |
ea = es (@Twb) - γ Pa(Tdb-Twb) where γ = 6.66x10^-4 |
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Methods of measuring air humidity |
1. Thermodynamic method 2. Change in physical dimensions of hygroscopic substances 3. Change in chemical and electrical properties of material due to absorption or adsorption 4. Condensation method 5. Spectral absorption of water vapor |
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Measures RH by giving wb & db temperature |
Psychrometer |
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Measures RH by means of variation in length of a strand of human hair |
Hair hygrometer |
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Uses cooled mirror as a sensor |
Dewpoint hygrometer |
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Higher absorption of infrared at higher water vapor concentration of air |
Infrared gas analyzer (IRGA) |
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Methods of measuring spectral absorption of water vapor |
1. Infrared gas analyzer 2. Lyman alpha hygrometer |
