posted on Jun, 27 2007 @ 08:41 PM
The tips of aircraft propellors are travelling very fast. In some aircraft they can actually exceed the speed of sound.
The high tip speed and the tip shape generates turbulence and shock waves. These air effects (under the right conditions) can cause atmospheric
moisture to condense into visible water vapour. They are, in effect, mini clouds that follow the propellor tips.
They are most likely to happen when the dew point temperature is very close to the actual temperature on days when there is a high degree of relative