TROPICAL CYCLONES:
A low-pressure cell that develops over warm oceans between the
tropics.
Bring violent weather conditions and cause great destruction
Aka. Typhoons – Japan & Eastern china, Hurricanes – Gulf of Mexico region, Cyclones –
South Africa, Willy willies – Australia
Named alphabetically, first letter tells us how many cyclones have occurred that year
Start at ‘A’ at the beginning of the new year
If it was a BAD cyclone the name is not used again!
Areas where tropical cyclones form:
Occur between 30˚N and 30˚S of the equator, DON’T occur between 5˚N&S of the
equator as they depend on THE CORIOLIS FORCE for formation (no Coriolis force
within 5˚ of the equator)
Usually occur on the EAST SIDE of continents (warmer ocean current; Agulhas
current)
Move from regions near the equator or towards coast of a country
When they reach land, turn eastwards away from coast and out to sea
Move EAST to WEST
Factors necessary for their formation:
1. hot air mass; develop at ITCZ (inter-tropical convergence zone) where moist, hot air
from tropical easterlies converge. Can only develop over sea where the temp is >
28˚C. This results in a lot of evaporation and very hot humid unstable air. (occur @
hottest times of the year, late summer & early autumn, sea has had time to warm
up)
2. Intense low-pressure cell, hot air rising forms an intense low pressure on the
surface. Tropical jet streams in upper air causes upper-air low pressure which
intensifies the LP cell on the surface, air is sucked into this LP cell.
3. Coriolis force = the force which deflects wind due to earth’s rotation on its axis.
Causes winds to spiral towards the LP cell and intensifies it to such an extent that a
CALM, CLOUD-FREE FUNNEL known as the EYE forms
Eye of the cyclone = calm area at the centre of a tropical cyclone
4. Continues to get energy: the large-scale condensation releases
LATENT HEAT into the atmosphere which provides the energy
needed to sustain the cyclone. The air is unstable which
contributes to air rising and the formation of LARGE
A low-pressure cell that develops over warm oceans between the
tropics.
Bring violent weather conditions and cause great destruction
Aka. Typhoons – Japan & Eastern china, Hurricanes – Gulf of Mexico region, Cyclones –
South Africa, Willy willies – Australia
Named alphabetically, first letter tells us how many cyclones have occurred that year
Start at ‘A’ at the beginning of the new year
If it was a BAD cyclone the name is not used again!
Areas where tropical cyclones form:
Occur between 30˚N and 30˚S of the equator, DON’T occur between 5˚N&S of the
equator as they depend on THE CORIOLIS FORCE for formation (no Coriolis force
within 5˚ of the equator)
Usually occur on the EAST SIDE of continents (warmer ocean current; Agulhas
current)
Move from regions near the equator or towards coast of a country
When they reach land, turn eastwards away from coast and out to sea
Move EAST to WEST
Factors necessary for their formation:
1. hot air mass; develop at ITCZ (inter-tropical convergence zone) where moist, hot air
from tropical easterlies converge. Can only develop over sea where the temp is >
28˚C. This results in a lot of evaporation and very hot humid unstable air. (occur @
hottest times of the year, late summer & early autumn, sea has had time to warm
up)
2. Intense low-pressure cell, hot air rising forms an intense low pressure on the
surface. Tropical jet streams in upper air causes upper-air low pressure which
intensifies the LP cell on the surface, air is sucked into this LP cell.
3. Coriolis force = the force which deflects wind due to earth’s rotation on its axis.
Causes winds to spiral towards the LP cell and intensifies it to such an extent that a
CALM, CLOUD-FREE FUNNEL known as the EYE forms
Eye of the cyclone = calm area at the centre of a tropical cyclone
4. Continues to get energy: the large-scale condensation releases
LATENT HEAT into the atmosphere which provides the energy
needed to sustain the cyclone. The air is unstable which
contributes to air rising and the formation of LARGE
