Once a tornado has reached the surface, the vortex, with its associated
updraft, launches all sorts of objects into the air. Dirt, grass, and leaves color the
clouds, giving them a bizarre aspect. Plumes of dust may rise up and surround
the funnel, making it look bigger than it actually is. As the vortex begins to dis-
sipate, it rises partially back into the mesocyclone, its path of destruction nar-
rowing and the damage becoming less severe. Small tornadoes sometimes
vanish abruptly, as if dissolving into the surrounding atmosphere. The base of
the mesocyclone swirls more slowly, until finally it is no longer evident. The
ragged cloud base, darkened by dirt pulled aloft during the life of the tornado,
still presents a threatening spectacle, but the danger has passed.
Once a thunderstorm has stopped producing funnel clouds, it normally
weakens and dissipates over an hour or two. Some thunderstorms generate tor-
nadoes for a while, weaken temporarily, and then strengthen again and spawn
more funnel clouds. This is most likely to happen in a multiple-cell system or
in a squall line.
STRANGE EFFECTS
Tornadoes are known for their awesome, and sometimes unearthly, methods of
destruction. Pine needles are driven into wooden planks, timbers hurled
through concrete walls, and trailers wrapped around trees. People have become
airborne in tornadoes—some inside vehicles or houses, and others all by them-
selves. Whole houses have been lifted off their foundations and moved several
meters without other structural damage. A tornado might reduce a house to a
pile of rubble, while the shade trees in the yard don’t lose a single branch. A
tornado once pulled a curtain through a sealed window around the edge (that is,
right through the seal!) without breaking the glass. In another instance, a
wooden beam passed through a piece of glass, punching a hole in the glass but
not shattering it.
If a tornado passes over unusually colored soil, the funnel and the whole
cloud base acquire the tint of that soil. This is responsible for the eerie light that
often precedes or accompanies a tornado. Ordinary soil produces a greenish or
yellowish hue. Some types of soil or sand can make the sky look pink, brown,
red, or even purple. If a tornado passes over a lake, stream, or swamp, the vor-
tex picks up fish and frogs. The creatures are carried by the updrafts within the
mother cloud, and later fall back to the earth along with rain or hail. If such a
storm passes over a populated area, the streets will be littered with fish and
frogs. Tornadoes have been known to strip chickens and other birds of their
feathers. Most of the birds are killed as they are flung about by the storm winds,
but some survive.
CHAPTER 5 Tornadoes
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