Why is it that in freezing temperatures, fog does not freeze up solid?

Answer 1

Cloud droplets don't freeze in the same way liquid water (like the water in a pond) does. They can become what's called "supercooled", in which they are below 0 deg Celsius but still in a liquid state. However, upon contact with a solid, subfreezing surface, they will form ice, often called "rime ice". This is the main reason it's dangerous to fly small planes in cold stormy weather - rime ice forms on their wings when they fly through clouds or fog, changing the shape of the wing profile and making the plane impossible to control.

Answer 2

You need to understand a few things. Fog is a condition of 100% humidity. But that does not mean that the air is 100% fog. It just means all the water that air can hold at that dew point and temperature has been acheived.

Fog is just a cloud formation that is able to exist at ground level. Exceed the 100% sutaration point and you get rain.

Also you need to realize fog is water vapor not water.

This does not meant that it can not freeze however.

There are 2 types of fog that actually do freeze.

One is Ice Fog. Ice Fog is a type of fog where droplets freeze into tiny ice crystals in mid air.

This is not an easy thing to acheived. It general requires temperatures be very cold. In the order of -30 F or 35 C. These kind of temperatures are only common in the Artic and Antarctic.

The second type is called Freezing Fog. Fog droplets make contact to a surface and freeze unto that surface.

Mountain tops are where that type of fog usual forms.

So fog can freeze solid.

It just takes very low temperatures and is only common in certain areas of the world.