In the case of freezing fog, the fog cloud droplets are supercooled. When a droplet contacts an object below freezing it will turn to ice. When only freezing fog occurs, there will be just about as much freezing of the fog droplets onto surfaces as there will be sublimation from the surface, thus there is not much accumulation of ice.
The tiny parcels of air cool and condense, which creates a cloud close to the ground. That’s the fog. (CBC Graphics) That process releases heat, and — because humid air is a better conductor of heat — it melts the snow quickly.
When a droplet contacts an object below freezing it will turn to ice. When only freezing fog occurs, there will be just about as much freezing of the fog droplets onto surfaces as there will be sublimation from the surface, thus there is not much accumulation of ice. Often freezing fog will be accompanied with freezing drizzle.
Fog can actually cause snow to melt faster. According to this site “In the spring, snowcover can melt rapidly if a warm, humid air mass overrides the snow and the snow then lowers the temperature of this humid air to the point that fog forms.
Why is there more fog on a cold front?
Since moisture is a key component for fog, advection from a moisture source is much more favorable than advection from a dry source. Widespread fog is more common with warm fronts than cold fronts. Part of the reason is that cold fronts tend to bring continental air (central and eastern US) while a south wind brings maritime warm air.
Why is there fog on top of the snow?
This is also why we tend to see a lot of fog (advection fog ) when milder air invades over the snow. Here’s the real trick – condensation involves 7.5 times more energy than melting does. What does that mean? For every molecule of water vapor that condenses, 7.5 bonds that are holding ice molecules together breaks.
This begs the question “Why do we see fog?”
You can see fog because of these tiny water droplets. Water vapor, a gas, is invisible. Fog happens when it’s very, very humid. There has to be a lot of water vapor in the air for fog to form. In order for fog to form, dust or some kind of air pollution needs to be in the air.
Fog is like a cloud on the ground. The way they are formed is different though. Clouds are mainly formed by rising air where fog is a few different ways that cause the air to be cooled to a point where it releases excess water droplets. One of these ways is when warm air melts the snow rapidly.
How does snow melt in the spring?
One of these ways is when warm air melts the snow rapidly. In the spring, snow cover can melt rapidly if warm, humid air pushes in above the snow and lowers the temperature of this humid air to the point that fog forms. The fog droplets forming at the snow surface release the latent heat of condensation, which helps to melt the snow.