When a physicist or a chemist is looking at the phase diagram of water then for him or her water, water vapour and ice are synonymous. Of course a common man will think that you have gone round the bend. Anyway I would like to get a technical thing out of our way. According to Wikipedia an HO-H bond of a water molecule (H-O-H) has 493.4 kJ/mol of bond-dissociation energy, and 424.4 kJ/mol is needed to cleave the remaining O-H bond. Now if even if one O-H bond is broken then it is no more water. So if we supply 424.4 kJ of energy then one mole of water will be dissociated - it will not be water. Thus to dissociate 6.022×10^23 bonds we need 424.4 kJ of energy. Or to dissociate one bond you need (424.4 divided by 6.022×10^23) kJ of energy. That is roughly 7×10^(-19) J of energy. Now Boltzmann's constant tells us that 1.38×10^(−23)J of energy equals one degree K. Thus 7×10^(-19) J of energy will equal (7/1.38)×10^(23-19)K in terms of temperature. This is 51068 K. Assuming I have not committed obvious mistakes. This is ten times the solar surface temperature. So at the solar surface water vapour can exist.