![Diagram of pressure drag over different shapes.](http://static.sciencelearn.org.nz/images/images/000/001/654/full/Pressure-drag20160808-15208-94nvii.jpg?1674166548)
Pressure drag is caused by the air particles being more compressed (pushed together) on the front-facing surfaces and more spaced out on the back surfaces. This is caused when the layers of air separate away from the surface and begin to swirl – this is called turbulent flow. Note how the wing shape reduces this.