Cyclones Flashcards
What is a tropical cyclone?
A rotating system of clouds and storms that form, and develop over tropical or subtropical waters
When is a tropical cyclone known as a hurricane?
Once its winds exceeds 118 km/h
Where are hurricanes commonly?
Used in North Atlantic and on the pacific coast of the USA
Where are cyclones commonly?
Used in the Indian and South Pacific Ocean
Where are typhoons commonly?
Used in the Western North Pacific
In the Northern Eastern Pacific Oceans and Atlantic Ocean what hurricane scale is used?
Saffir-Simpson scale
In Western Pacific what scale is used?
Meterological Agency scale is used
In Australia what cyclone scale is used?
Australian tropical cyclone intensity scale
What 4 main hazards do cyclones cause?
Strong winds
Storm surges
Intense rainfall
Landslides
What do strong winds involve?
Able to whip up garden furniture, lift roots, vehicles
They bring down trees, destroy whole buildings
What do storm surges involve?
Bring flooding caused by unusually high tides
High tides are even higher than normal during a cyclone due to low air pressure
Sea level is raised due to less weight of air holding it down
High tides extend inland causing coastal flooding
What does intense rainfall involve?
With thick dense clouds
Not unusual for 1000 mm of rain to fall in a single storm
What do landslides involve?
Landslide is a movement of rock, debris or earth down a slope
Caused when ground is saturated by rain causing it to slump
How long to tropical cyclones average across?
650km
What are the areas known as where tropical cyclones form?
Source regions
What are the three conditions for tropical cyclones to form?
A large, still warm ocean - surface temperature exceeds 26.5 degrees over a long period of time
Strong winds in the troposphere, 10-12km above earth’s surface which is needed to draw warm air up rapidly from ocean surface
A strong force caused by Earth’s rotation called Coriolis force. Tropical cyclones DO NOT form near the equator where Coriolis force is minimal but instead between 5-30 degrees latitude
Describe the basic formation of a hurricane/ cyclone
Warm air currents rise from the ocean
Updraughts of air contain water vapour from oceans which condenses and produces cumulonimbus clouds
Coriolis force causes rising of air to spiral around the centre of the tropical cyclone
As tropical cyclone tracks away from its source, it is fed new heat and moisture, enlarging it
Once it reaches land mass it loses energy source from ocean. Air pressure rises as temperature falls,winds drop, rainfall decreases and it decays to become a mere storm
Why don’t cyclone form at the equator?
Because the Coriolis force is weaker and minimal as it is on,y 5-30 degrees latitude
Why do cyclones form over oceans and decay over land?
Over oceans they have more energy but over land they lose their energy as air pressure rises causing temperature to drop and wind to fall
Why is the eye of the storm the calmest part?
There are no clouds so there is no rain
Which state did Hurricane Katrina hit?
New Orlean, Lousiana
What temperature must the ocean water be for a Tropical cyclone to form?
26.5 degrees Celsius
What is vulnerability?
A measure of the extent to which a community or area is likely to be damaged or disrupted by the impact of a hazard
What is a risk?
Probability of a hazard event causing harmful consequences
What factors affect vulnerability?
Preparation Education Population density Building design Time of day Economy Sediment type
