84% of evaporated water vapour is from the oceans, the other 16% is evaporated from the land. 75% of precipitation falls on the oceans, the other 25% falls on land. The excess water is returned to the oceans via streams and groundwater. Water from the ocean is heated and evaporates (requires energy to transfer from liquid to gas) Water vapour ascends in the atmosphere due to convection (temperature decreases with height) As water vapour rises, it undergoes condensation, which creates clouds (releases energy when going from gas to liquid) Any transfer of states involves the exchange of energy. If there is constant water cycling, there is a constant flux up due to convection. This energy flux from the surface of earth should be included in our calculations. We do not include it though because it is constant in all models. Earth is warming but water cycling increases flux out of the earth. It has long term effects on the atmosphere.