Planes, The Rainmakers

Aeroplanes can punch holes through the clouds and trigger rain and snow fall. Researchers have found this happens under certain atmospheric conditions—cloud layers with temperatures of -15°C or lower.

When planes fly through these layers, the tips of their propellers make the surrounding air rapidly expand and cool. The supercooled water droplets in the clouds then freeze into ice particles and turn into snow or rain as they fall. Science,

Source: Down To Earth, August, 2011