what is the height of fog. how variable is it.?

Question

i just wanna know this b coz every year lot of flights are delayed due to fog .so upto what height sky is free from fog.

Answer 1

Fog is low lying clouds.. they can go up very high.. depending upon the humidity and the pressure.

Answer 2

Fogs of all types are generally found below a temperature inversion in the temperature lapse rate. A temperature inversion is a cap which prevents or inhibits vertical motion from below to penetrate above the inversion. It traps both pollution and fogs below. The bases of an inversion are normally pretty low but can be as high as a 1000 feet. I believe it is at times such as those when fog is dense and extends through a substantial depth of the inversion that aircraft takeoffs may be held up until the inversion is said to break and the fog dissipates. The current weather observation under these conditions would state "indefinite zero ceiling and zero miles visibility in fog".

Answer 3

Fog is cloud at ground level and planes can fly in cloud (fog). It's taking off and landing in fog which is problematic. So it's not so much the height of the fog which is the issue but whether it's foggy at ground level.

As to the question about what height is free from fog, clouds above about 20,000 feet are usually thing wispy strands, above about 6000 feet tend to be the light fluffy ones and below 6000 feet they're usually the thick gray type. A notable exception are storm clouds which can be in excess of 40,000 feet high.