SWIRLING vortices caused by jet planes taking off and landing may linger in the atmosphere long enough to interfere with the next plane off the tarmac. These vortices form pairs of horizontal tornadoes that can spin at speeds of around 360 kilometres an hour.
Philip Saffman and David Hill at the Californian Institute of Technology ran mathematical models to see how crosswinds would affect the vortices. They found that a crosswind could cause one of the pair to hang around for up to 15 minutes (Proceedings of the Royal Society A, vol 458, p 1527). Planes only have to be…
