Atmospheric Triple Point

[Old Smokey]

Can anyone advise of the pressure (or equivelant Pressure Height) in the atmosphere whereafter water exists in 2 states only, ice or water vapour, with no liquid state between?

I had it in my notes some years ago when I was doing some University lectures on Aerodynamics, but lent it to one of the students who permanently borrowed it.

enicalyth, your name comes to mind as a possible source of all wisdom regarding atmospheric water vapour.

Thanks in advance,

Smokey