Fog

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Low level cloud

Fog forms near the ground when water vapor condenses into tiny liquid water droplets that remain suspended in the air. It is accurate to describe fog as a cloud near the ground.

Types of Fog

Advection Fog- fog formed after evening rain, due to the soaked ground in combination with the cooling nighttime air.

Precipitation Fog- fog formed beneath precipitation producing clouds. Precipitation fog often occurs due the precipitation falling from the clouds coming in contact with the drier air below. The drier air causes for the water droplets to evaporate into water vapor. In general, the saturation of air below the clouds causes for fog to form.

Upslope Fog- Upslope fog forms when winds blow up the side of a hill or mountain. As the air from the wind rises to higher elevation it expands and cools. If air cools enough, the humidity in it begins condensing into fog, clouds, rain, or snow.

Valley Fog- This very thick fog forms in mountain valleys during winter and can be more than 1,500 feet thick. The tendency for cool dense air to stay at the bottom of a valley causes for the fog.