How long does it take for water to evaporate?
The rate that water evaporates can indeed be calculated, but it depends on a few more things than you mention. The evaporation rate is influenced by 1) The temperature of the water at the air-water surface 2) The humidity of the air 3) The area of the air-water surface 4) The temperature of the air (more on this below) In a real-world situation of evaporating water, none of these three quantities above remains constant because the process of evaporation itself changes them. Water evaporating takes quite a lot of heat away — 540 calories per gram — when it evaporates. That’s enough to cool down 540 grams of water by a degree, or 50 grams of water a little more than ten degrees. If you are not very careful to replace the lost heat energy during the evaporation, the temperature will go down. And even then the temperature right at the surface will be lower than elsewhere in the water and it will depend on 5) water currents convecting heat and the ability to keep the temperature constant
