It is actually water vapor condensation, the same as when we exhale in cold weather. (colstrip-united.org)
A new theory on how water vapor condensation influences atmospheric pressure and dynamics». (rabett.blogspot.ru)
According to our estimates, convection accounts for 67 %, water vapor condensation in troposphere accounts for 25 %, and radiation accounts for about 8 % of the total heat transfer from the Earth's surface to troposphere. (scienceofdoom.com)