Question

Why the blowing of air from small opening of mouth feels cooler?

Answer 1

Hello mate,✌

Here is your answer:-

It is mainly due to air entrainment.

If you blow through a tight mouth, there is smaller volume of air but a higher velocity. This pulls in and mixes with a lot of ambient air (Venturi or Bernoulli effect) - in fact typically the air stream is only 40% body warmth and 60% ambient so it will be markedly colder. As an experiment you pucker and blow through a tube held to your mouth, this excludes the ambient air and you will get reduced airflow but at the higher temperature again.

With a wide mouth there is hardly any air entrainment. Its temperature will be almost same as its temperature in your lungs which is higher than the ambient temperature.

Hope it help ^_^

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