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Posted by on Jun 20, 2016 in Tell Me Why |

Is There Any Difference Between Fog and Clouds?

Is There Any Difference Between Fog and Clouds?

No – fog is actually a cloud which lies close to the ground. Clouds form wherever the air cools below the dew point – where the air is too cold to contain all its water vapor. Below that temperature, some of the air’s moisture condenses around tiny specks of dust in the air.

When air rises and cools high in the sky, water vapor condenses and forms tiny droplets which we see as clouds. When droplets form at ground level, however, these clouds are called fog. Fog usually forms where cold ground or water cools low-lying air below its dew point.

There are many different types of fog, too. Ice fog forms when the air near the ground is cold enough to turn the water in fog into ice crystals. Ice fog forms only at extremely cold temperatures. Ice fog is common in parts of Alaska and Canada.

Another kind of fog is freezing fog. Ice crystals form in the air when it’s cold enough and particles like dust or smoke in the air provide a “seed” for the ice crystal to form around. Sometimes it is cold enough, but the air does not have any particles.

In this case, water in the air becomes “super cooled.”  This super cooled water is a liquid, but it is colder than the freezing point (32ºF). When it comes into contact with cold surfaces such as roads and sidewalks, it instantly forms a dangerous icy layer.

One of the most troubling kinds of fog is called “super fog.” Super fog forms when smoke from wildfires and water vapor come together to form an extremely dense fog. The smoke provides particles for the water vapor to condense around. This combination of smoke and water vapor is a dangerous one.

A super fog is so dense that you would not be able to see your own hand in front of your face. Super fogs create very hazardous driving conditions.

Content for this question contributed by Shannon Fry, resident of Aptos, Santa Cruz County, California, USA