Water is, mostly, only added to the atmosphere by evaporation. This is mostly solar, but can include indirect solar (wind) and industrial processes. Rain 'see

Water is, mostly, only added to the atmosphere by evaporation. This is mostly solar, but can include indirect solar (wind) and industrial processes. Rain 'seeding' can be thought of as offering water already in the atmosphere an excuse to form rain and drop out of the atmosphere. It's about controlling where it rains rather than if it rains.