Volcanos and Fog
Why does fog form over volcanoes?
There could be a couple of reasons that you see fog
or clouds above volcanoes.
Many active volcanoes are still emitting gases,
which contain water vapor. At the height of the top
of te volcano, it is often quite cold, so the water vapor
condenses into fog or cloud (fog is really just a cloud
near the ground).
Another possibility is that air is being lifted over the
volcano; the air has to go somewhere, so when the wind blows
air towards the volcano, the air has to either go around the
volcano or rise above the volcano. Air cools as it rises
and if it cools enough to bring the water vapor in the air
to the condensation point, a cloud will form over and/or
around the top of the volcano.
David R. Cook
Climate Research Section
Environmental Science Division
Argonne National Laboratory
The "fog" you see above volcanoes is a mixture of smoke and hot
steam that has condensed in the cooler atmosphere. The steam comes
from water from deep within the Earth.
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Update: June 2012