Dew point

Dew point, air temperature at which water vapor turns to liquid. Through a process called condensation, moisture (dew) forms on plants and outdoor surfaces when the relative humidity in the air is 100% and a cooling process occurs around the exposed surfaces. Excessive condensation attained at dew point results in the formation of fog. Water formed at dew points below freezing temperature (32°F, 0°C) yields frost.