True Tornado Tail Tale
[Part 2 of 6] Slowly writhing in the rain, the snakelike tail of the funnel lowered and oscillated up and down. Such motion in a condensation funnel isn't really the tornado itself going "up and down," but instead, a result of changes in the visible cloud that happen because of fluctuations in either the temperature, the air moisture content or the tornado's pressure perturbation (pressure compared to surrounding air). Dry up the inflow air, warm it, or raise the pressure, and the funnel may appear to lift. Cool and moisten the inflow air and/or strengthen the tornado by lowering its pressure, and the funnel appears to dip. Either way, the wind (true tornado vortex) still is there until the air becomes too stable to keep it going, or until dynamic changes in the storm kill the vortex.
11 E St. Peter KS (22 May 7), looking N.