The change of state that occurs during evaporative cooling (from a liquid to a vapor) requires the removal of 970 BTUs per pound of water.
Evaporative cooling is a very powerful source of heat transfer.
I am not taking this course so I don't know which are specifically looking at (and probably neither do you). We need more information.
Surface tension of the water (barometric pressure) and the wetbulb temperature determine the specific rate of latent heat transfer through evaporation. 100% Rh and no evaporation takes place.
I don't know the answer. I'm just asking if you are sure.
If you can detect evaporative cooling at the surface, than it will affect the temperature of the body of water. Infrared thermal imagers can detect very low temperature differentials.
Besides evaporative cooling, water changes temperature at a different rate than the ambient air. It is nearly impossible to have "steady-state conditions" in building evaluation (this is one of the reasons that thermal imaging on buildings is one of the most complex applications for thermal imaging and should not be blown off as simple point and shoot photography).
Conditions are constantly changing and there is a lag factor for water which will cause it to show up when it is not under a steady-state condition.
Another consideration; conductivity is faster through water than through air.
Another consideration; "air film" is an insulating buffer around objects. Air is a good insulator and reduces heat transfer through convection and conduction.
When you guys try to evaluate a infrared thermal imaging scan, you need to ask yourself why things are as they seem and assess the conditions and factors that produce the conditions you are seeing. Should the object be hotter or colder? Why? The camera cannot collect all the information you need. You have to take into account other variables that require other test equipment or procedures (not taught in infrared training) to acquire the information necessary for an accurate assessment.
In reality, the thermal imaging camera is not even a thermometer, as everyone seems to use it as.