Science behind fog

Published: Dec. 13, 2022 at 2:39 PM CST
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QUAD CITIES, Iowa/Ill. (KWQC) - Fog has been a common occurrence over the last week across the Quad Cities area, but how does it form? There are two types that are common in the QCA this time of year; advection fog and radiation fog.

Advection fog develops when relatively warm, moist air moves over a cold surface, such as land and/or water, leading to the temperature near the ground to cooled to saturation.

This typically occurs with a warm front passing in the winter, especially when snow is on the ground. Radiation fog happen during the overnight hours when there is a clear sky and a calm wind and happens during radiational cooling.

At night, the longwave radiation emitted by the ground leads to the ground cooling, which causes warmer temperatures above, known as an inversion.

The moist air below the inversion cools to the dewpoint, and depending on the moisture present, fog can form, and it can be locally dense at time.

When driving in foggy conditions, be sure to slow down and allow extra time to reach your destination. Leave plenty of distance between your vehicle and the vehicle in front of you.

Make sure your vehicle is visible to other ahead of, and behind you by using low-beam headlights, or fog lights if you have them.