| Hurricanes
can spawn tornadoes
Even if you're not in Hurricane Katrina's path, you may be feeling its effects
if a tornado comes nearby. Scientists have discovered that hurricanes can actually
encourage the formation of tornadoes. When meteorologists studied hurricane-related
damage, they found some damage that didn’t fit the pattern, and discovered
it was actually damage resulting from hurricane-related tornadoes.
How tornadoes form
Air is a gas and water is a liquid, but in the realm of
science, both fall into the category of fluids. When a fluid's flow is disturbed
somehow, it causes turbulence. For instance, branches sticking into and under
the water can disrupt the flow of a stream, forming tiny eddies or whirlpools.
The same thing happens when you move your hand quickly through water. Technically,
these are known as vortices. The water moves in a circular motion around a central
point, and this causes a depression or cavity to form in the center, which draws
flowing objects towards that center. Think of water spinning down the bathroom
drain.
These sorts of swirling vortices can also form in air. As a thunderstorm develops,
if the wind speeds up and changes direction, this can cause a horizontal spinning
effect in the lower atmosphere. As air rises, pulled upwards by the developing
thunderstorm, it tilts the horizontal rotation into a vertical rotation. A tornado
is simply a violently rotating column of air that extends from a thunderstorm
in the atmosphere to the ground. The pressure inside can be 10% lower than the
surrounding air, and this causes that air to rush towards the low-pressure center
from all directions. As it streams inward, the air spirals upward around the
core until it merges with the airflow of the thunderstorm that gave rise to the
tornado.
Tornado safety tips
- Move to a pre-designated shelter, such as a basement
- Stay away from windows
- Get out of automobiles; don’t try to outrun a tornado
- Abandon your mobile home; they offer little protection from tornadoes.
- An underpass is not safe: debris can fly underneath it and be deadly. Instead,
head for a ditch.
The American Meteorological Society contributed to the information contained
in the TV version of this report.
Go inside this science
American Meteorological Society
45 Beacon Street
Boston, MA 02108-3693
Telephone: (617) 227-2425
|
|
