Martian atmosphere is full of water  Posted by Emma Woollacott
The Martian atmosphere contains water vapor in a supersaturated
state, say surprised ESA scientists.  On Earth, water vapor
tends to condense into a liquid when the temperature falls below
dewpoint. At this point, the atmosphere is said to be
'saturated', since it can't hold any more moisture at that
temperature and pressure.  However, condensation can sometimes
be much slower, especially when particles around which the water
molecules can coalesce are scarce. The excess water vapor then
remains in the gaseous state, in a phenomenon known as
supersaturation.  Until now, it was assumed that supersaturation
couldn't occur in the Martian atmosphere - but ESA says that
data from the Mars Express spacecraft leaves no room for doubt.
Surprisingly, while several spacecraft have visited Mars, most
of their instruments have been focused on surface data. The way
in which water content on Mars varies with height remained
largely unexplored.  But observatio