What increases the rate of evapotranspiration?

What Drives Evapotranspiration?

Evapotranspiration is the combined process of water evaporating from the soil and transpiring through plants. When trying to understand what accelerates this natural water loss, meteorologists and hydrologists look closely at four key weather parameters: solar radiation, air temperature, humidity, and wind speed.

Solar radiation provides the primary energy source needed to turn liquid water into vapor, meaning bright, sunny days naturally see higher rates. Air temperature goes hand in hand with sunlight, as warmer air has a greater capacity to hold moisture. Conversely, humidity works in the opposite direction; dry air with low relative humidity creates a steeper moisture gradient, pulling water away from surfaces much faster than humid air. Finally, wind speed keeps the air moving, constantly sweeping away saturated air from plant leaves and soil surfaces and replacing it with drier air, which further speeds up the process.

To measure the combined drying power of these atmospheric conditions, scientists use a standard metric known as reference crop evapotranspiration (ETo). By calculating ETo using these core weather variables, researchers and farmers can accurately gauge how much water the atmosphere is demanding from the landscape at any given time.