I measured the temperature of water and found that it's less than room temperature. I think evaporation is the main reason of it. Are there any reason except evaporation for the less temperature of water?
I also noticed that the temperature difference between water and air increases when humidity decreases.
Water was on a aluminium bowl. After sometimes the water temperature increases but can't beat the air temperature
Best Answer
It is normal for water temperature to be less than air temperature because evaporation takes heat from the water. With lower humidity in the air, evaporation is greater, increasing the temperature difference. I cannot think of any other reasons off the top of my head, and I am fairly sure there aren't any, excepting, of course, the fact that water from the tap may well be colder than room temperature, because it comes from storage where it is colder.
You will only get an equal temperature if the air is saturated with water vapour. To put that in perspective, typically air near the surface of the Earth is about 50% - 70% saturated. Deserts can be below 30%, whereas Manchester averages between 80% and 90% saturation. To obtain equal temperature, you would need to put the bowl of water into an enclosed system, which would ultimately obtain 100% saturation if you could insulate it sufficiently to maintain constant temperature (or maybe measure it on a rainy day in Manchester, but not indoors in a heated environment).