Why is air  cooler when you blow it out with your lips closer to each other WHICH IS WITH MORE PRESSURE AS LIPS ARE CLOSER SURFACE AREA IS LESS SO PRESSURE IS HIGH as opposed to with your mouth wide open(WHICH IS WARM)?BUT WE ALSO KNOW THAT TEMPERATURE DECREASES AS PRESSURE DECREASES SO ALSO EXPLAIN WHY IN THIS SITUATION OPPOSITE HAPPENS THAT IS PRESSURE INCREASES THEN TEMPERATURE DECRESES?EXPLAIN IN DETAIL

Asked by abinash.gupta003 | 2nd Nov, 2017, 01:34: PM

Expert Answer:

When the mouth is wide open, the area is more, so a lot of warm vapour from inside the
human body comes out. It comes out at a slow rate. But when the area is slow and the mouth
is not wide open it comes at a faster rate but in less quantity at a time.
This gets cooled down by surrounding air.
The moment it touches the skin (suppose skin of hand) it will increase the rate of evaporation which
makes the temperature at that spot to reduce.
This is not possible when the rate is slow and warm air coming out is more in quantity when the mouth is wide open.

Answered by Gajendra | 4th Dec, 2017, 11:46: AM