A presentation on ''How various Factors affecting Evaporation "

1. PRESENTED BY-PRESENTED BY-
PRATEEKPRATEEK

3. SOME DEFINATIONSSOME DEFINATIONS
 Evaporation:-
conversion of a liquid to a vapour.
 Transpiration:-
that part of evaporation which enters the
atmosphere through plants.
 Total Evaporation:-
the combined processes of evaporation and
transpiration .
this has been referred to as evapotranspiration.

4. EVAPORATIONEVAPORATION
 Evaporation is a type of vaporization of a liquid that occurs
from the surface of a liquid into a gaseous phase.

5. REASON FOR EVAPORATIONREASON FOR EVAPORATION

7. FACTORS AFFECTINGFACTORS AFFECTING
EVAPORATIONEVAPORATION
 Various factors affecting the rate of evaporation are:-
1) Concentration of the substance evaporating in the air.
2) Concentration of other substances in the air.
3) Temperature of the substance.
4) Flow rate of air.
5) Inter-molecular forces.
6) Surface area and temperature.
7) Humidity.

8. FACTORS AFFECTINGFACTORS AFFECTING
EVAPORATIONEVAPORATION
1. Concentration of the substance evaporating in
the air.
 If the air already has a high concentration of the
substance evaporating, then the given substance will
evaporate more slowly.

9. FACTORS AFFECTINGFACTORS AFFECTING
EVAPORATIONEVAPORATION
2) Concentration of other substances in the air :-
 If the air is already saturated with other substances, it can have
a lower capacity for the substance evaporating. I.e.. The rate of
evaporation of substance is less.
.

10. FACTORS AFFECTINGFACTORS AFFECTING
EVAPORATIONEVAPORATION
3) Temperature of the substance.:-
 If the substance is hotter, then evaporation will be faster. As
the temperature of air is increased, its capacity to hold
moisture also increases.
 Increase in air temperature provide more energy to molecule
to change its state. Hence evaporation is directly proportional
to the temperature of evaporating surface.
 Warmer the evaporating surface, higher the rate of
evaporation
.

11. FACTORS AFFECTINGFACTORS AFFECTING
EVAPORATIONEVAPORATION
4). Flow rate of air :-
 Molecules in motion have more energy than those at rest,
and so the stronger the flow of air, the greater the
evaporating power of the air molecules.
.

12. FACTORS AFFECTINGFACTORS AFFECTING
EVAPORATIONEVAPORATION
5). Inter-molecular forces
 The stronger the forces keeping the molecules together in the
liquid or solid state the more energy that must be input in order to
evaporate them.
.

13. FACTORS AFFECTINGFACTORS AFFECTING
EVAPORATIONEVAPORATION
5). Surface area and temperature
 The rate of evaporation is determined by the area of the
exposed surface of water. Larger areas of evaporating surface
increase the rate of evaporation.
 A larger surface area allows more molecules or atoms to leave
the liquid, and evaporation occurs more quickly.
 For example, the same amount of water will evaporate faster
if spilled on a table than if it is left in a cup.

14. FACTORS AFFECTINGFACTORS AFFECTING
EVAPORATIONEVAPORATION
5). Humidity
 The rate of evaporation is closely related with the relative
humidity of air.
 the moisture holding capacity of air at a given temperature is
limited, drier air evaporates more water than moist air .
 In other words, higher the vapour pressure, lower the rate of
evaporation.
 It is a common experience that evaporation is greater in summer
and at mid-day than in winter and at night.
.