
Why exactly is there apparently steam coming off him though?
Because the sweat evaporates, this cools down the body.
Now, air is a gasmixture as we all now. it can only contain a certain amount of watervapor before it is saturated.
2 factors here come in effect
1) very cold temperature : the air can hold much less watervapor at low temperatures
2) its raining : when its raining, the air will allready be close to saturation point. around 80% iirc
what happens here is, his sweat evaporates in nearly saturated air, the air close to his body gets saturated, and because of this, there is a condensation back into water, and immediate re-evaporation.
this cases a white mist.
If you would place a fluid in a closed chamber, and heat it, you can see this very clearly that the air gets very foggy. this is again because the saturationpoint is reached.
