What is the pan evaporation rate during rainy days?
Answers
Explanation:
Evaporation is a process by which liquid transformes in to gas or
vapors. The atmosphere receives its supply of moisture from the earth‟s
surface through evaporation from oceans, lakes, rivers etc, and takes about
600 calories water of energy to convert 1 gram of water vapor (Robertson,
1955). During evaporation, water molecules absorb energy which gives
them the motion required to escape from the surface of liquid and become
gas. This energy is subsequently released as heat when condensation takes
place, and water vapor changes back to the liquid state. The heat absorbed in
the process of evaporation is referred to as the latent heat of evaporation.
Latent heat means hidden or stored heat. Since a certain amount of energy is
consumed in the process of evaporation the remaining liquid is cooled by an
equivalent amount (Carder,1960).
Evaporation is a cooling process and it has cooling effect on
evaporating bodies. When the rain drops fall through the dry layers of
atmosphere, the process of evaporation chill the air. This is so because most
of the energy needed for evaporating water which is provided by the air it
self.
Since temperature is the primary control of evaporation naturally
decrease from the equator towards the north. However, actual evaporation is
different from potential evaporation. Besides temperature, wind speed and
relative humidity, it also depends on the available water to be evaporated on
land surface. In fact, the evaporating power of air is many times greater than
the available water supply. Water entering the evaporation phase of the
hydrological cycle becomes unavailable and cannot be recovered for further
use. This is an important consideration in the planning and management of
water resources.