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Meteorology
Advection fog over land is most common during the winter months. In the
spring and autumn months, advection fog can form over water when heated
air over land blows out over the colder water.
3.6.6.3 Orographic fog
Orographic fog forms when stable, moist air is forced up a sloping terrain (e.g.,
mountains), and it cools down, resulting in condensation and cloud formation
that remains on the ground.
3.6.6.4 Front fog
Front fog forms in front of
a warm front.
The fog forms from the
evaporation of warm
raindrops that fall through
an area of cooler air.
A mixture of the warm raindrops with the surrounding cold air causes the air to
become saturated, resulting in condensation, which forms stratus or front fog.
The fog usually dissolves when the sun heats the air, causing it to evaporate.
Initially, the fog may lift into low clouds, but if the sun takes effect properly,
such as when the clouds break, it happens very quickly.
Wind uplift will also help dissipate the clouds. Precipitation can remove
moisture from the fog. This happens when larger raindrops capture the small
fog droplets, causing the fog to dissolve.
Fog cannot exist for a long time over cold snow.
Flight Theory PPL(A)(UL)/LAPL Henning Andersen, Midtjysk Flyveskole© 2025 289
