7.4: Clouds and Precipitation
Condensation occurs either near the surface or aloft and results in the formation of small droplets of water. Condensation at the surface results in dew formation when the near surface air temperature drops to the dew point temperature. This often occurs at night under cloudless skies when the air is humid. Under cloudless skies, emitted terrestrial radiation penetrates to space, cooling the surface which then cools the near surface air.