Which factors affect the rate of evaporation from water and soil surfaces?

In hydrologic sciences, the rate of evaporation from water and soil surfaces is governed by several interconnected physical factors that influence the transition of liquid water into water vapour.12

The primary factors affecting these rates include:

• Solar Radiation: This is a critical energy source that warms the evaporating surface, increasing the vapour pressure at the surface and providing the necessary latent heat to facilitate the phase change.342
• Temperature: Evaporation generally increases with higher surface temperatures. The temperature difference between the evaporating surface and the surrounding air is a key driver of the process.32
• Relative Humidity: Evaporation rates are higher when the air is drier. The process is proportional to the saturation deficit, which is the difference between the vapour pressure in the free air and the saturation vapour pressure at the surface.342
• Wind Speed: Increased ventilation or wind speed removes moisture-laden air from the surface, maintaining a steeper vapour pressure gradient and enhancing the rate of diffusion.342
• Soil Moisture: For soil surfaces, the availability of water is a limiting factor. As soil dries, the rate of evaporation decreases because water must diffuse through soil pores to reach the surface.15

Additionally, transpiration from plants often acts in tandem with direct evaporation, a combined process known as evapotranspiration.15