2007-01-06 01:54:31 · 7 answers · asked by gaelgale 1 in Science & Mathematics ➔ Weather
This is an answer I gave recently to a similar question.
While fog and cloud look much the same from inside and fog in mountainous areas is often cloud, fog generally is not cloud on the ground.
The ground cools overnight by radiating into space. The cool ground in turn cools the air above that which in turn cools the air above that. Thus there is a layer of cold air close to the ground. The greatest rate of cooling occurs when there is no cloud and little or no wind.
There is always water vapour in the air. This is the gaseous form of water. The water vapour is condensing into water droplets and the water droplets are evaporating. This goes on all the time. Usually the rate of evaporation exceeds the rate of condensation and the air is clear.
There is a temperature at which the rate of condensation equals the rate of evaporation. This is called the Dew Point. The Dew Point differs for each air mass depending on the amount of water vapour in the air but can be measured easily.
If the temperature falls below the Dew Point, as it could close to the ground in the cool air I spoke of earlier, then the rate of condensation exceeds the rate of evaporation and liquid water condenses out of the air.
On very still mornings, this liquid water deposits itself on the ground, rocks, motor cars etc and we call it dew. If there is a very light wind, the air very close to the ground will be mixed with the air a little higher and the water droplets will stay suspended in the air. We call this suspension of water doplets "fog". Once the sun comes up and the air temperature rises above the Dew Point, the fog evaporates.
2007-01-06 07:27:13 · answer #1 · answered by tentofield 7 · 0⤊ 0⤋
Fog is a cloud in contact with the ground. Fog differs from other clouds only in that fog touches the surface of the Earth. The same cloud that is not fog on lower ground may be fog where it contacts higher ground such as hilltops or mountain ridges.
2007-01-06 09:57:21 · answer #2 · answered by tampico 6 · 0⤊ 1⤋
you can not see the clouds for the fog !, because the fog is the cloud, but rather than high in the sky is on the ground in order to say high to us !
2007-01-06 09:59:30 · answer #3 · answered by Anonymous · 0⤊ 0⤋
Fog is caused by warm air meeting cool air when cool air meets warm it is forced to rise and thats what causes fog
2007-01-06 18:29:43 · answer #4 · answered by Anonymous · 0⤊ 0⤋
fog is a cloud that has moisture in it
2007-01-06 10:00:19 · answer #5 · answered by karen b 2 · 0⤊ 0⤋
from were the clouds come from the fog do
so we don't have a fog from clouds we have directly fog
2007-01-06 09:58:25 · answer #6 · answered by Raoof 2 · 0⤊ 1⤋
omg, i just learned this in science yesterday!!!!
fog is a cumulus (i believe) cloud that is just close to the ground. it's water vapor.
2007-01-06 09:56:57 · answer #7 · answered by Emma 2 · 0⤊ 2⤋