The vortices are created at the plane's wingtips as the wings generate lift. The lower pressure air above the wing and the higher pressure air below seek to balance out, which causes the spiraling air flow. The vortices can continue spiraling in the air even minutes after an aircraft has passed.

When wing tip vortices do occurs?

As the air curls upward around the tip, it combines with the downwash to form a fast-spinning trailing vortex. These vortices increase drag because of energy spent in producing the turbulence. Whenever an airfoil is producing lift, induced drag occurs and wingtip vortices are created.

Which type of aircraft creates wingtip vortices?

The strongest vortices are produced by heavy aircraft, flying slowly, with wing flaps and landing gear retracted ("heavy, slow and clean"). Large jet aircraft can generate vortices that can persist for many minutes, drifting with the wind.