Radiation Fog
3 definitions

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Fog produced over land when radiational cooling reduces the air temperature to or below its dew point. It is also known as ground fog and valley fog.

FK Reading Ease
61.5

FK Grade Level
Middle School
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  • This definition has not yet been approved by a moderator.

    A common type of fog, produced over a land area when radiational cooling reduces the air temperature to or below its dewpoint.

    Thus, a strict radiation fog is a nighttime occurrence, although it may begin to form by evening twilight and often does not dissipate until after sunrise. Factors favoring the formation of radiation fog are 1) a shallow surface layer of relatively moist air beneath a dry layer and clear skies, and 2) light surface winds. It can be most confusing near sea coasts with cold coastal water. It can be difficult at times to differentiate between this and other types of fog, especially since nighttime cooling intensifies all fogs. Radiation fog is frequently and logically called ground fog, but in U.S. weather observing practice, the latter term is defined only with respect to the amount of sky that is obscured by the fog.

    FK Reading Ease
    53.9

    FK Grade Level
    High School
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  • Fog produced over the land by the cooling of the lower atmosphere as it comes in contact with the ground. Also known as ground fog.

    FK Reading Ease
    82.5

    FK Grade Level
    Elementary School
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