Grade 12
Name: ……………………...
Term one
CHAPTER 2 tropical CYCLONES
1
, Develops over
warm oceans
between tropics
Cell of very
intense low
pressure system
associated with
severe storms, strong
winds and heavy rain.
Tropical cyclone
Represented by circular isobars
Enclosing an area of intense low
pressure
Clockwise wind circulation in
southern hemisphere
Very steep pressure gradient =
very strong winds
Very destructive to humans and
environment
Torrential rain & storm surges
Hail, lightening & thunder
Very strong winds
Destructive weather conditions
NORTHERN HEMISPHERE SOUTHERN HEMISPHERE
Convergence of air in an Convergence of air in a
anti-clockwise direction, clockwise direction,
Deflection of air (HP—LP) Deflection of air (HP—LP)
to the right (Coriolis Force) to the left (Coriolis force)
2
, Tropical cyclone: Scale
Tropical cyclones are categorised
on a scale of 1 to 5
Most only reach level 3 and then
dissipate / disappear
Categories 4 and 5 are the most
dangerous
!
Naming tropical cyclones
Named with people’s names starting with a name
beginning with A for the first tropical cyclone of the
season.
We are able to determine how many other tropical
cyclones have already occurred in that season in
that region.
Tropical cyclone Eline was the fifth one
in the 2000 season (February).
Four tropical cyclones preceded Eline.
A tropical cyclone is smaller
(300-500km in diameter) than
a mid-latitude cyclone (up to
3000km) BUT the intensity
and threat is much greater!
3
Name: ……………………...
Term one
CHAPTER 2 tropical CYCLONES
1
, Develops over
warm oceans
between tropics
Cell of very
intense low
pressure system
associated with
severe storms, strong
winds and heavy rain.
Tropical cyclone
Represented by circular isobars
Enclosing an area of intense low
pressure
Clockwise wind circulation in
southern hemisphere
Very steep pressure gradient =
very strong winds
Very destructive to humans and
environment
Torrential rain & storm surges
Hail, lightening & thunder
Very strong winds
Destructive weather conditions
NORTHERN HEMISPHERE SOUTHERN HEMISPHERE
Convergence of air in an Convergence of air in a
anti-clockwise direction, clockwise direction,
Deflection of air (HP—LP) Deflection of air (HP—LP)
to the right (Coriolis Force) to the left (Coriolis force)
2
, Tropical cyclone: Scale
Tropical cyclones are categorised
on a scale of 1 to 5
Most only reach level 3 and then
dissipate / disappear
Categories 4 and 5 are the most
dangerous
!
Naming tropical cyclones
Named with people’s names starting with a name
beginning with A for the first tropical cyclone of the
season.
We are able to determine how many other tropical
cyclones have already occurred in that season in
that region.
Tropical cyclone Eline was the fifth one
in the 2000 season (February).
Four tropical cyclones preceded Eline.
A tropical cyclone is smaller
(300-500km in diameter) than
a mid-latitude cyclone (up to
3000km) BUT the intensity
and threat is much greater!
3
