Mesocyclone
That is, it is air that rises and rotates around a vertical axis, usually in the same direction as low pressure systems in a given hemisphere. They are most often cyclonic, that is, related with a localized low pressure area inside a severe thunderstorm. Such storms can create strong surface winds and a lot of hail. Mesocyclones often happen together with updrafts in supercells, where tornadoes may form.