Breath Temperature

[PeterJB]

An interesting question came up in my Physics class yesterday, which, although unrelated to physics, promped much discussion, but no conclusive answer was made.

So, basically, why is it that when you breathe onto the palm of your hand at close range, that the air is warmer than if you blow it on to the palm of your hand?

 

[Submerged]

Wouldn't you have more sensitive receptors on the palm and fingers than the back of the hand?

 

[PeterJB]

It's the palm of the hand both times, should have cleared that up.

 

[Neal]

The short answer is evaporation. Blowing onto your hand means more moisture on your skin evaporates making it feel cool. Breathing slowly causes less evaporation so feels warmer.

 

[ECGadget]

Evaporation is the short answer