Dynamic Pressure

Quite simply, if you hold your hand up in a strong wind or out of the window of a moving car, then the extra wind pressure is felt due to the air impacting your hand. This extra pressure is over and above the (always-present) static pressure, and is called the dynamic pressure.

The dynamic pressure is due to relative movement. Dynamic pressure occurs when a body is moving through the air, or the air is flowing past the body. Dynamic pressure is dependent on two factors:

- The speed of the body relative to the flowstream. The faster the car moves or the stronger the wind blows, then the stronger the dynamic pressure that you feel on your hand. This is because of the greater number of air molecules that impact upon it per second.

The density of the air. The dynamic pressure depends also on the density of the air. If the flowrate was the same, and the air was less dense, then there would be less force and consequently a lower dynamic pressure.

Dynamic pressure depends upon air density