I've always wondered what really caused it...i want to be able to predict it better...the most thorough and easy to follow explanation will get the 10 points.
2007-01-03 07:39:41 · 9 answers · asked by Matt B 2 in Science & Mathematics ➔ Weather
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.
2007-01-03 08:06:12 · answer #1 · answered by tentofield 7 · 0⤊ 0⤋
Fog is caused by by moisture in the air turning into fine vapour droplets - this happens when the temperature drops to what is called the 'dewpoint'.
'Dewpoint' is simply a term which means that the air cannot hold all of its water as vapour and so the water becomes liquid.
Often you will see mist or fog forming on fields or around rivers, this is because of low ground temperature cooling the air. Effectively, fog is just a cloud at ground level.
The seasons also affect the degree to which fog forms. Autumn is often described as the 'season of mellow fruitfulness' and is characterised by early morning mist.
A more scientific, but less poetic description might be 'the season of radiation fog'! (Caused by water evaporating from land and water and being affected by infra red cooling.)
Fog can be made worse by pollution and so is thicker and more persistent some areas.
2007-01-03 15:41:43 · answer #2 · answered by Scott H 2 · 2⤊ 0⤋
Don't let people trick you by them saying that fog is clouds close to the ground. That is totally fake! No, fog is moister that is in the air, humidity. Evaporation.
2007-01-03 15:49:20 · answer #3 · answered by Midget 2 · 1⤊ 0⤋
Fog is created when clouds are down pretty much on the ground. If its thick fog there is probobly more than one cloud.
2007-01-03 15:43:18 · answer #4 · answered by Sonya B 1 · 0⤊ 1⤋
cold, moist air coming in contace with warmer air. when the two air masses come together, the moisture in the air forms tiny droplets of water, which we see as fog.
2007-01-03 15:42:40 · answer #5 · answered by wrldzgr8stdad 4 · 0⤊ 0⤋
fog is clouds that are very low to the ground.
2007-01-03 15:41:30 · answer #6 · answered by Anonymous · 1⤊ 1⤋
condensation (water droplets) and a change in air pressure or temperature
2007-01-03 15:42:01 · answer #7 · answered by G 0324 2 · 0⤊ 0⤋
It caused by moisture!
2007-01-03 16:16:49 · answer #8 · answered by Anonymous · 0⤊ 1⤋
its nothing more then a cloud that is to heavy to remain airborne
2007-01-03 15:41:50 · answer #9 · answered by jthaney92 1 · 0⤊ 1⤋