dewdrop

A dewdrop is a small drop of liquid water that forms on cool surfaces by the condensation of water vapor from the air, typically appearing overnight or in the early morning.

It forms when ambient air is cooled to its dew point and the surface is at or below that temperature in a humid environment. Surfaces such as grass blades, leaves, spider webs, and window glass commonly host dewdrops. They are usually 0.1 to 2 millimeters in diameter.

The droplets are mainly pure water, though they may contain small amounts of dust, organic matter, or dissolved salts scraped from the surface. They are typically clear and form spherical shapes thanks to surface tension; evaporation can occur rapidly in sunlight.

In nature, dewdrops contribute transient moisture and can influence the microclimate on leaf surfaces. Dew harvesting is explored in arid regions, using specialized collectors or roughened surfaces to promote condensation and capture water for local use.

Dew should be distinguished from frost; dew forms as liquid water, whereas frost results when freezing temperatures convert water vapor directly into ice. Dew is also related to general leaf wetness, which affects plant physiology and disease dynamics.