Long smooth boundary layers between moist air and dry air are the target of vortice growth

http://www.thunderbolts.info/forum/phpBB3/viewtopic.php?f=10&t=16329&start=210#p122376

You can’t understand tornadoes (and/or jet streams) unless and until you understand how the composition of the sheath of a tornado is molecularly distinct from that of the air that surrounds it and that moves up through it.