Mesozyklone

A mesocyclone is an area of vertical atmospheric rotation, typically 2-6 miles across. They are often found in the right-rear flank of supercell thunderstorms, and are visible as a hook echo on Doppler weather radar. The presence of a mesocyclone can only be truly verified by radar, although visual clues such as curved inflow bands may be present.

Mesocyclones form when strong changes of windspeed and/or direction with height ("wind shear") sets the lower part of the atmosphere spinning horizontally. The updraft of a thunderstorm can then draw this area of spinning air from horizontal to vertical.

See Also: Supercell