Ivy asked in Science & MathematicsWeather · 1 month ago

How would you calculate specific humidity of an air parcel from temperature and water vapor mixing ratio?  eg: 20˚C and 10 g/Kg?

1 Answer

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  • TQ
    Lv 7
    1 month ago

    Specific humidity is the ratio of the MASS of water vapor to the TOTAL MASS of the system ... expressed as g/kg.

    Specific humidity = MASS of water vapor / TOTAL MASS of water vapor

    Specific humidity = mixing ratio (W) / saturation mixing ratio [W(s)]

    Specific humidity = W / W(s)

    Specific humidity = 10 / saturation mixing ratio @ 20°C

    W(s) = 6.11 * 10 ^ (( 7.5 * T ) / (237.7 + T))

    W(s) = 6.11 * 10 ^ ((7.5 * 20) / (237.7 + 20))

    W(s) = 6.11 * 10 ^ (150 / 257.7)

    W(s) = 6.11 * 10 ^ 0.582

    W(s) = 6.11 * 3.820

    W(s) = 23.34

    Specific humidity = 10 / 23.34 = 0.42 = 42%

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