dewy

Dewy describes something covered with or resembling dew, the tiny droplets of liquid water that form on surfaces in the presence of moisture and cool temperatures. The term can also refer to the fresh, moist appearance characteristic of early morning landscapes.

Dew forms when water vapor in the air condenses on surfaces that have cooled to or below the dew point, typically overnight. Radiative cooling of surfaces such as grass blades, leaves, spiderwebs, and car roofs causes nearby air to reach saturation, leading to droplet formation. The size and distribution of droplets depend on humidity, wind, surface roughness, and the duration of cooling. Dew disappears as surfaces warm with sunrise and evaporation increases.

Dew is liquid water droplets; frost, by contrast, consists of ice crystals that form when temperatures fall below freezing. Condensation is the broader process, which can produce dew, fog, or clouds depending on conditions.

Ecological and practical aspects include dew contributing a modest amount of moisture to plants in arid or Mediterranean climates and influencing leaf microclimates and disease dynamics. Some cultures historically collected dew as a supplemental water source. In agriculture, heavy dew can promote foliar diseases on crops and ornamentals.

Measurement and terminology involve the dew point temperature—the temperature at which air becomes saturated and condensation begins. Tools such as hygrometers and dew point meters assess moisture conditions that predict dew formation.

Etymology traces dewy to the Old English deaw (dew), related to Dutch dauw and German Tau, reflecting its long-standing observation in temperate climates.

See also: condensation, humidity, dew point, frost.