radiation fog

American  

noun

1. fog produced by the nocturnal cooling of the surface boundary layer to a temperature at which its content of water vapor condenses.

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Etymology

Origin of radiation fog

First recorded in 1855–60

Example Sentences

Technically known as radiation fog, it can develop in any valley, but the geography of the Sacramento and San Joaquin valleys can make it particularly intense, resulting in several massive freeway pileups in recent years.

From Los Angeles Times • Dec. 9, 2025

This makes the air denser and increases relative humidity, condensing more water vapor, and resulting in a phenomenon known as radiation fog.

From National Geographic • Feb. 16, 2024