Top-Down Process / Dynamic Pipe Effect
•With this process, tornadoes descend from
midlevels within the thunderstorm and then emerge from the
base of the wall cloud.
•A narrowly constricted flow in the middle
atmosphere that might develop when the mid-level mesocyclone is
stretched.
•Air entering this narrow “pipe” from below
must itself constrict as it approaches the entry point.
•That constriction in effect lowers the
“pipe”, and the constriction grows downward.
•When the constricted “pipe” reaches the ground, tornadoes
touchdown occur.