TROPICAL CYCLONES
A low pressure system that develops over the warm tropical waters and
moves in the easterlies
General characteristics:
1. Form between 5° - 20° north and south
[they don’t form in 0° - 5° due to the zero effect of the coriolis force]
2. Isobars form concentric circles around a central low pressure
3. The pressure at the centre is very low - usually 960 hPa
4. Approximate diameter is between 600 - 1000km
5. Travel at 10 - 20km/h - can cover up to 200km a day
6. Last about a week once meeting the mature stage
7. System does not meet the land
8. Form in late summer & early autumn - when latent heat is at its peak
9. Process of development - dependent on the central air pressure
[tropical depression -> tropical storm -> tropical cyclone]
10. Classified as a tropical storm when when speeds reach more than
65kph - the point at which they are named
[cyclones are named alphabetically, alternating between boy & girl names -
this is an indication of how many cyclones have occurred in a season]
Latent heat - ‘hidden’ heat energy absorbed and stored in water vapor
during evaporation and is released during condensation
, WHERE TROPICAL CYCLONES FORM:
Occur in the tropical latitudes (5° - 20°)
Do not occur at the equator do to lack of the coriolis effect
Occur over warm oceans - Atlantic Ocean is too cold
Tend to form on the eastern coast of continents - warm currents
Blow from east to west, but sometimes tend to curve north in the
northern hemisphere and south in the southern hemisphere
Conditions necessary for the formation of TC’s:
Sea surface temperature of at least 27°C
Means that the air sitting on the sea surface can rise rapidly,
initiating a central LP
Energy used for evaporation is released as latent heat -
providing the necessary energy for the cyclone to develop
Coriolis effect - causes the air to rotate around the low pressure
centre, strengthen and move away from the equator
Moisture further up in the atmosphere to allow for vertical cloud
development
Instability in the upper air encourages cloud development &
divergence - allowing for continued rising
A low pressure system that develops over the warm tropical waters and
moves in the easterlies
General characteristics:
1. Form between 5° - 20° north and south
[they don’t form in 0° - 5° due to the zero effect of the coriolis force]
2. Isobars form concentric circles around a central low pressure
3. The pressure at the centre is very low - usually 960 hPa
4. Approximate diameter is between 600 - 1000km
5. Travel at 10 - 20km/h - can cover up to 200km a day
6. Last about a week once meeting the mature stage
7. System does not meet the land
8. Form in late summer & early autumn - when latent heat is at its peak
9. Process of development - dependent on the central air pressure
[tropical depression -> tropical storm -> tropical cyclone]
10. Classified as a tropical storm when when speeds reach more than
65kph - the point at which they are named
[cyclones are named alphabetically, alternating between boy & girl names -
this is an indication of how many cyclones have occurred in a season]
Latent heat - ‘hidden’ heat energy absorbed and stored in water vapor
during evaporation and is released during condensation
, WHERE TROPICAL CYCLONES FORM:
Occur in the tropical latitudes (5° - 20°)
Do not occur at the equator do to lack of the coriolis effect
Occur over warm oceans - Atlantic Ocean is too cold
Tend to form on the eastern coast of continents - warm currents
Blow from east to west, but sometimes tend to curve north in the
northern hemisphere and south in the southern hemisphere
Conditions necessary for the formation of TC’s:
Sea surface temperature of at least 27°C
Means that the air sitting on the sea surface can rise rapidly,
initiating a central LP
Energy used for evaporation is released as latent heat -
providing the necessary energy for the cyclone to develop
Coriolis effect - causes the air to rotate around the low pressure
centre, strengthen and move away from the equator
Moisture further up in the atmosphere to allow for vertical cloud
development
Instability in the upper air encourages cloud development &
divergence - allowing for continued rising
