In this the contact separation and arc extinction occurs in a high pressure air chamber.
The air flowing axially at high speed along the arc causes removal of heat from the periphery of the arc and the diameter of arc reduces to a low value at current zero.
At this natural current zero instant the arc is interrupted and contact space is flushed with fresh air flowing through the nozzle.
The flow of fresh air through the contact space ensures removal of hot gases and rapid building up of dielectric strength.[This is a 2 minute concept sketch drawn especially for exam point of view.