hurricanes are often confused. Think of The Wizard of Oz and it
should cunjure up visions of one of these weather phenomenom.
Do you know which one? (check the bottom of the page to see if
occur in most parts of the world. However they are most frequent
over the continental plains of the USA.
are typically identified as a funnel of spiralling air descending
from the base of clouds to the earth. The tornado is usually narrow,
about 1/2 km wide and rarely does it move more than 20 km.
the precise mechanism of how the funnel forms in not understood.
start within 8º and 15º north and south of the equator where surface
sea temperatures reach 27ºC. The air above the warm sea is heated
and rises. This causes low pressure.
The weather system generates heat which powers the storm, causing
wind speeds to increase. This causes the Tropical Storm to sustain
itself. Tropical storms rely on plenty of warm, moist air from
the sea - this is why they die out over land.
part of the tropical storm is known as the eye. The eye is usually
between 30-50km across. It is an area of calm, with light winds
and no rain. It contains descending air. Large cumulonimbus clouds
surround the eye. These are caused by moist air condensing as
it rises. Wind speeds average 160km per hour around the eye. You
can read more about tropical storms here.
and 15º north and south of the equator
parts of the world
over warm seas
over land and sea (they are known as water spouts over the
click your red shoes and watch out for tornadoes carrying houses!