Evapotranspiration is defined as the total amount of water used by the planets in transpiration and evaporation from adjacent soils, at any specified time.

Generally, it is the sum of evaporation and transpiration from the ground surface to the atmosphere. Evapotranspiration is also called Consumptive Use.

The evapotranspiration process is important for the water cycle process of the earth. The evapotranspiration process is the combined process of evaporation and transpiration, which means the forming of clouds, humidity, vapor in the atmosphere, etc. depends on evapotranspiration.

As per the research, the Evapotranspiration process is responsible for 15% to 20% of the atmosphere’s water vapor.

This means if the evapotranspiration process not happened, so there is no rainfall because without water vapor input how clouds are formed, and, if clouds not formed so there is no precipitation.

that is the simple reason, why Evapotranspiration is important.

Evaporation is a process in which water converts from liquid to gaseous form that is vapor due to high temperature.
Evaporation in evapotranspiration is referred to as the water evaporated from ocean, river, lake, ponds, soil, wetlands, standing water, etc.
While
Evapotranspiration is the combined process of evaporation and transpiration

Evapotranspiration rate is the ratio of the amount of water evaporated from cropped area to per unit water depth.

Evapotranspiration is expressed in millimeters (mm).

Lysimeters and Field plots are used to measure Evapotranspiration.

The factors affecting evapotranspiration are given below.
1. Meteorological Factor
2. Density of vegetation
3. Soil Moisture
4. stage of plant growth
5. Adjoining Land
6. Surface of leaves

Evapotranspiration can be measured with the help of Phytometer.
Phytometer method:
T = (M1-M)+M2

Where,
M1 = Initial mass of the instrument
M2 = Final mass of the instrument
M = Total mass of water added during full growth of the plant.
T = Loss due to Transpiration