A cooling mechanism to condense the water vapor into liquid or ice. Rising air is the cooling mechanism to create clouds.
Fog is formed by five different cooling mechanisms.
Condensation nuclei such as smoke, pollen, dust, pollution, etc. Water Vapor Water vapor is invisible and is measured by the amount of pressure it exerts on a surface. Water vapor pressure is denoted as e . The average atmospheric pressure is 1013.2 mb, of which 0 to about 40 mb is made of water vapor. Water vapor content depends upon having a source for water to evaporate such as an ocean, lake, wet ground, etc.