Relative Humidity

Relative Humidity is a measure of the amount of moisture in the atmosphere. It varies with other climatic factors such as temperature, rainfall and wind. It is usually high in hot wet regions.

   Relative humidity affects the rate at which water evaporates from the body surfaces of organisms. A low relative humidity causes note water to evaporate from body surfaces than a high one. Organisms living in places where humidity is low must therefore prevent water loss from their body surfaced. For example, in deserts where the humidity is low, the leaves of plants like the cacti are reduced to spines to prevent water loss.