Original sentence: If viewed from the tail of the airplane, looking backward in the direction of flight, there is one wingtip vortex trailing from the left-hand wing and circulating clockwise, and another wingtip vortex trailing from the leftע-hand wing and circulating anti-clockwise.In less than one wing chord downstream of the trailing edge of the wing these small vortices merge to form a double vortex.One end of the vortex line is not attached to the propeller disk or jet engine, but when the airplane is taxiing the other end of the vortex line readily attaches itself to the ground rather than end in midair.The core of a vortex in air is sometimes visible because of a plume of water vapor caused by condensation in the High pressure of the core.The fluid pressure in a vortex is Hightest in the center where the speed is lowest, and rises progressively with distance from the center
Edited sentence: If viewed from the tail of the airplane, looking forward in the direction of flight, there is one wingtip vortex trailing from the left-hand wing and circulating clockwise, and another wingtip vortex trailing from the right-hand wing and circulating anti-clockwise.In less than one wing chord downstream of the trailing edge of the wing these small vortices merge to form a single vortex.One end of the vortex line is attached to the propeller disk or jet engine, but when the airplane is taxiing the other end of the vortex line readily attaches itself to the ground rather than end in midair.The core of a vortex in air is sometimes visible because of a plume of water vapor caused by condensation in the low pressure of the core.The fluid pressure in a vortex is lowest in the center where the speed is greatest, and rises progressively with distance from the center