Dewfall

Dewfall is the process by which atmospheric water vapor condenses onto surfaces as liquid water during the night or early morning. This phenomenon occurs when the surface temperature drops below the dew point of the surrounding air. The dew point is the temperature at which the air becomes saturated with water vapor and condensation begins.

Several factors contribute to dewfall. Radiational cooling is a primary driver, where surfaces lose heat to the atmosphere overnight, causing their temperature to decrease. Surfaces that are good radiators, such as grass, leaves, and smooth rocks, tend to accumulate more dew. The presence of sufficient water vapor in the atmosphere is also essential. Calm or lightly breezy conditions are more conducive to dewfall than strong winds, as wind can mix warmer air with the cooler surface air, preventing condensation.

Dewfall plays a significant role in ecosystems. It can provide a crucial source of moisture for plants, especially in arid or semi-arid regions where rainfall is infrequent. It also supports a variety of small organisms, such as insects and microbes, that rely on this moisture. For humans, dewfall has historically been a source of water collection, though it is generally not a significant source for large-scale use. The formation of dew is a common sight in the morning, often appearing as tiny droplets on vegetation and other exposed surfaces.