Understanding Rotors: Local Wind Circulations 🌬️

Rotors are a small-scale overturning circulations that cause localised changes in wind direction and speed. They are associated with high-amplitude mountain or lee waves. <br /><br />They are sometimes visible through a roll of cloud that seems to rotate on itself, and they can cause problems for aircraft.<br /><br />For rotors to form we need a mountain range to provide the conditions for lee waves to form, a temperature inversion sitting above the mountain top and winds blowing across the range at a speed of around 30 mph.<br /><br />Rotors develop during mountain wave conditions because of changes of pressure and wind at the surface that accompany lee waves. <br /><br />Small areas of low and high pressure exist respectively with the troughs and crests of the waves. <br /><br />Wind at the surface accelerates beneath the troughs and decelerates beneath the crests.