It is an interesting topic. We have some industrial customer heats up the water to 99.9 degC before injection, so the evaporation is almost instant there by producing a fully humidify air very quickly for the fuelcell reactor. I am not sure if there are any cooling effect. Almost injecting liquid steam.
On the other end of the scale, cool your water to sub-zero temperature by adding some methanol (-90C freezing point), If you store this mixture in a thermos, it should have a dramatic cooling effect when the atomised mixture meets the air. It should be similar to surfing closely behind a snow making machine at 100mph (imagine you are the incoming air travelling towards the spray jet).
