Answer: The correct answer for the blank is- Sublimation.
Sublimation can be described as a process according to which water in a solid form ( which could be in the form of snow or ice) changes directly into a gaseous form ( that is in the form of water vapors).
It adds water to the atmosphere in the form of vapors. This process requires heat absorption and thus it is an endothermic process.
Therefore, in cold and snowy areas, water is added to atmosphere through sublimation.
