Variation In Relative Humidity
Diurnal variation in RH
The diurnal variation in relative humidity is approximately inverse to that of temperature about sunrise the RH is maximum and between 14 to 15 hrs minimum RH is observed.
Annual variation in RH: The annual variation of relative humidity is largely depends upon the locality.
At regions where the rainy season is in summer and winter is dry, the maximum relative humidity occurs in summer and minimum in winter and at other regions maximum RH occurs in winter.
Over ocean RH reaches maximum in summer.
Variation of RH with latitude and altitude:
RH shows maximum at equation or about 80%. Therefore it decreases to 70% in the regions of high pressure belts in 30-350 and afterwards increases again to 80 to 90% in the polar region.
The vertical variation of RH is not governed by any exact law. In or near the clouds it is 100% but below or above it is different. The moist air masses carried out by advection at altitudes also change relative humidity.