There have been times when we tried to warm our hands by snoring in the cold or when we burned ourselves, we tried to cool them by blowing. So how does this difference occur?
In fact, the air that comes out of our mouths is generally at the same temperature. Since the temperature of the air coming out of our mouths does not change much, there is another reason behind this. We have compiled these reasons for you.
First of all, the main reason for this situation is mouth movement.
In other words, when you say ‘hoh’, since the oral cavity is larger, the flow of air coming from and out of the lungs will be lower. So its speed is even slower; naturally, when the speed is slow, the heated air in the lungs gets even hotter until it comes out of the mouth.
When blowing or puffing, the oral cavity is narrower. Therefore, the flow rate of the flowing air is fast. Contrary to the other E, the air will flow quickly on the path from the lungs to the mouth, so it is thrown out without heating.
If you ask what is the flow rate of the air; It is the amount of fluid passing through a certain area per unit time. So what is mentioned is actually the flow rate of the air.
When you blow through pursed lips (as when whistling), you create a fast-moving stream of air.
Fast-moving air (your breath) creates turbulence when released into relatively still air (the air around you).
The effect of turbulence is that it pushes the surrounding stagnant air out of your mouth into the air. Just like in the photo above. The blue arrows show the air surrounding you, and the black arrow the air coming out of your mouth. The air outside our bodies is always slightly cooler than the air coming out of our lungs.
The air that reaches your hand is cold, as the colder air from the surrounding is drawn into the warmer air stream coming out of our mouths. In fact, most of the air you feel in your palms as you blow through pursed lips is the surrounding air.
When you blow through a wider mouth, as in the photo above, the air comes out at a slower rate, as when you say ‘haah’. Because of this, it doesn’t create the same turbulence as faster airflow and, accordingly, draws much less volume of surrounding colder air into your warmer breath.
It also has to do with the proximity of what we blow to our mouth. For example, when blowing, bring your hand as close to your mouth as possible; The air coming out will be hot, and when you move it away, it will cool.
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