How Does Wind Speed Affect Evaporation Rates?

Increased wind speed accelerates the rate of evaporation, because it keeps the relative humidity of the air right above the water from rising. Additionally, the wind moves and disturbs the surface of the water, which causes the water to evaporate more quickly. The drier the air being blown across the surface of the water is, the more quickly the water evaporates.

The air can hold some water, but for any given temperature, there is a limit to its water-holding capacity. When air has all of the water it can carry, it is called “saturated,” meaning that the relative humidity is 100 percent. When the air is saturated, the water’s rate of evaporation and condensation achieve equilibrium, meaning that water is evaporating into the air at the same rate that water is condensing out of the air. If the wind is not blowing at all, the molecules of water that turn into the gaseous state tend to accumulate right over the surface of the water. The relative humidity of this layer of air soon approaches saturation levels, and no more evaporation takes place. However, if the wind blows air across the surface of the water, the water vapor is carried away. Simultaneously, new, drier air replaces the damp air, accelerating the rate of evaporation.