Hello everybody, A friend of mine asked me a question regarding one of his milk-processing techniques. He wants to learn if a mathematical formula or a logical approach can be devised. Okay, the question involves a 1 liter-volume-bowl, whose outer (bigger) radius is 160 mm. He didn't say the inner (lower) radius of the bowl, as I think he considered it not important. He places hot milk at 80°C inside the bowl, and after three hours, he sees that the temperature is lowered to 40°C. He is wondering the amount of water vapor (humidity) evaporated, but in a theoretical basis. I suggested him that he can try simple weighing measures at different intervals, but he insists on seeing a theory-based calculation scheme. Any suggestions?