Diurnal Variation of Humidity

By day, as the temperature increases, RH will decrease because the maximum amount of water vapour air can hold increases as the temperature rises. 

After 1500 hrs, the temperature will start to fall and the maximum amount of water vapour the air can hold will fall and thus the RH will increase. The higher RH at night is the reason for the formation of mist and fog after dark in autumn and winter. 

When the air is cool (morning), the relative humidity is high. When the air is warm (afternoon), the relative humidity is low. These conditions exist in clear weather when the air is calm or of constant wind speed. RH tends to be highest when it is coldest.

RH is maximum approximately 30 minutes after sunrise when the temperature is minimum. 

error: Content is protected !!