[ajmaferreira]

Is it possible to have a balloon (or a vessel) whit water vapour at zero degrees and  normal pressure?
I'm talking about a meta stable situation or something like that...

[Shiryatsya]

At zero degrees Kalvin? No that would be the only circumstance where H2O would not have a vapor pressure [but then you wouldn't have a pressure of 1 atm, it is impossible to reach 0K but if you did pressure would have to be equal to zero]. HOWEVER assuming you mean 0* C and and 1 atm (where the solid and liquid states are in equilibrium) there is in fact a vapor pressure. According to this link from Cal Tech http://www.its.caltech.edu/~atomic/snowcrystals/ice/Vapor2.gif it's approx 6 mBar

[First post... hope I didn't violate any rules or something]