I found it very interesting phenomenon and I began to inventigar and I found a pretty reasonable assumption:
As the air comes from inside of our lungs, is about the body temperaturea 
and let him out without any interference by the open mouth is hot air. Useful to tarnish the crystal glasses before cleaning, heating blue with cold hands or try to raise the temperature to simulate fever thermometer.
The only modification of the mouth opening gives it more speed, but make no extra effort. So we blow candles bubbles collect or we turn a paper mill. But also lowers its temperature, which is very useful to us to cool the soup or stew too hot to soothe the skin in a minor burn or sting of alcohol on a wound.
But ... what should the temperature change?
When blow keep your mouth almost closed so that air is forced out through an opening much closer. And when a fluid with a constant flow passes through higher to a lower section necessarily its speed increases, as indicates the fluid dynamics, namely the Venturi effect. And if the kinetic energy, which is determined the speed increases, the energy determined by the value of the pressure must necessarily decrease as the theorem of conservation of energy or Bernoulli's principle.
Being out of the mouth and reduced pressure, the air expands. Joule-Thomson says that if a gas expands freely, its temperature decreases as the distance between the molecules is higher and its energy is diluted in a larger volume. Therefore, the blowing air having a temperature lower than the breath.
and let him out without any interference by the open mouth is hot air. Useful to tarnish the crystal glasses before cleaning, heating blue with cold hands or try to raise the temperature to simulate fever thermometer. The only modification of the mouth opening gives it more speed, but make no extra effort. So we blow candles bubbles collect or we turn a paper mill. But also lowers its temperature, which is very useful to us to cool the soup or stew too hot to soothe the skin in a minor burn or sting of alcohol on a wound.
But ... what should the temperature change?
When blow keep your mouth almost closed so that air is forced out through an opening much closer. And when a fluid with a constant flow passes through higher to a lower section necessarily its speed increases, as indicates the fluid dynamics, namely the Venturi effect. And if the kinetic energy, which is determined the speed increases, the energy determined by the value of the pressure must necessarily decrease as the theorem of conservation of energy or Bernoulli's principle.
Being out of the mouth and reduced pressure, the air expands. Joule-Thomson says that if a gas expands freely, its temperature decreases as the distance between the molecules is higher and its energy is diluted in a larger volume. Therefore, the blowing air having a temperature lower than the breath.
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