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Transcript of Cyclones
A cyclone is a low-pressure system that develops over warm tropical waters and is sufficiently intense. As it produces sustained gale force winds of at least 63 km/h on average that rotate in a clockwise circulation.
How a cyclone develops
We advise you to take notes during this presentation as they would become very handy in the end
Cyclones are called
in the Atlantic and eastern Pacific,
in Southeast Asia, and
in the Indian Ocean and western Pacific and of course Australia.
But they are not called cyclones all around the world!
Map of tropical cyclone route in Australia, 2012-2013
Cyclone category table
The patterns of cyclones in Australia
The cyclones are mostly located on the north east and north west of Australia.
They are located where the weather is very hot or tropical.
The cyclones start at the Indian Ocean and the Coral Sea.
How are cyclones formed?
It only takes two main things to start a tropical cyclone: a cluster of storms and a warm body of water with a temperature of at least 26-27°C (from which the storm gathers its energy). These conditions are mostly found between the latitudes of 5 degrees and 30 degrees on both sides of the equator.
So the warm water also warms the air, this creates areas of intense low pressure and encourages water to evaporate. The evaporated water molecules rise into the sky, eventually rising to such a point that they condense into clouds. When many clouds form in one place in a way that could lead to the formation of a cyclone, it is called a tropical depression.
As more clouds build up, the energy released by the rising, cooling air and water causes the air pressure to drop further. This energy combined with the rotation of the Earth gets the cyclone spinning and propels it forward.
Loss of vegetation and the habitats or wildlife
Short-term heavy rains and flooding
Mud slides and soil erosion
Saltwater intrusion to underground fresh water reservoirs
The contamination or water from saline water
Storm surges and tides
Damage to offshore coral reefs and natural defence mechanisms
Waste and debris accumulation (some which might be hazardous)
Impacts associated with reconstruction and repair to damaged infrastructure e.g. deforestation, quarrying, waste pollution
• Loss of income
• Some businesses close down and people are left unemployed
• Reduced income for businesses affected by damage resulting from the cyclone.
• Farmers suffer from crop damage or livestock losses, and on Australia's eastern coast, this specifically affects Australia's specialized tropical fruit industry.
• Local businesses may have building damage and lose some of their produce. This drives up prices of goods and supplies
• There are enormous costs - sometimes hundreds of millions of dollars
The destruction of buildings, resulting in people finding themselves homeless
People often have to leave the area which means they lose everything.
The wiping out of businesses or agricultural crops means that some families may be left without an income for which they can even rebuild with.
How to protect yourself from a cyclone
Disconnect all electrical appliances
Listen to your battery radio for updates
Stay inside and shelter (well clear of windows) in the strongest part of the building,
i.e. cellar, internal hallway or bathroom. Keep evacuation and emergency kits with you.
If the building your in starts to break up, protect yourself with mattresses, rugs or blankets under a
strong table or bench or hold onto a solid fixture, e.g. a water pipe.
. If the wind drops, don't assume the cyclone is over; violent winds will soon resume from another direction.
Wait for the official 'all clear'.
If driving, stop (handbrake on and in gear) - but well away from the sea and clear of trees,
power lines and streams. Stay in the vehicle.
As a tropical cyclone spins, it generates high winds heavy rainfall and large storm surges. In the southern hemisphere, cyclones spin in a clockwise direction while in the northern hemisphere they spin in an anti-clockwise direction. The storm is then pushed on by winds in a largely westward direction.
While a cyclone may look savage from the outside, its eye (low-pressure center) is very calm with only a few clouds. It is surrounded by an enormous and dense wall of clouds which is 16 kilometres high this wall is the deadliest part of a cyclone as it is where the strongest winds and rainfalls are found.
The eye is usually between 10km-48km in diameter, while the whole storm is usually 400-600km in diameter.
On early Christmas morning, the tropical weather depression named
hit the northern Australian city of Darwin.
As the cyclone passed over the city it destroyed buildings and houses, the sounds of breaking glass and flying debris filled the air. Winds over 217 km/h were detected, and torrential rain flooded the city.
Cyclone Tracy was a
category four cyclone
. The reason why the cyclone caused so much damage is because the eye of the storm passed directly over the city. The eye of the cyclone passed over the city between midnight and 7.00 am.
After the cyclone passed, the widespread damage it caused was seen. It destroyed 70 per cent of Darwin’s homes and all public services like communications, power, water and sewerage were detached. 65 people were killed, 49 on land and 16 at sea, and many more were injured.
Damage to Darwin after Cyclone Tracy
The satellite photo shown, is Cyclone Tracy approaching Darwin three days before it hit.
Levels of Government
Check with your local council or your building control authority to see if your home has been built to cyclone standards.
Check that the walls, roof and eaves of your home are secure.
Trim treetops and branches well clear of your home (get council permission).
Preferably fit shutters, or at least metal screens, to all glass areas.
Clear your property of loose material that could blow about and possibly cause injury or damage during extreme winds.
In case of a storm surge/tide warning, or other flooding, know your nearest safe high ground and the safest access route to it.
Prepare an emergency kit containing:
a portable battery radio, torch and spare batteries, water containers, dried or canned food and a can opener, matches, fuel lamp, portable stove, cooking gear, eating utensils, first aid kit and manual, masking tape for windows and waterproof bags.
Keep a list of emergency phone numbers on display.
Check that neighbours are aware of the situation and are preparing.
If a neighbour knocks on your door before the cyclone, with their kit and they think in confidence that their house isn't strong enough let them in.
If requested by local authorities, collect children from school or childcare centre and go home.
Park vehicles under solid shelter (hand brake on and in gear).
Put wooden or plastic outdoor furniture in your pool or inside with other loose items.
Close shutters or board-up or heavily tape all windows. Draw curtains and lock doors.
Pack an evacuation kit of warm clothes, essential medications, baby formula, nappies, valuables, important papers, photos and mementos in waterproof bags to be taken with your emergency kit. Large/heavy valuables could be protected in a strong cupboard.
Remain indoors (with your pets). Stay tuned to your local radio/TV for further information.
Evacuate the area
Stay with their home hoping that it will keep them safe
Check neighbours, especially if recent arrivals, to make sure they are prepared.
Listen to community alerts.
Warn people, that the cyclone is approaching their area,
Tell them how to evacuate (if needed)
Tell people the four different stages of alerts.
Give warnings to the people, that the cyclone is approaching their area,
Give instructions to radio stations, to tell the people what to do next.
Cyclonic question time!
Now to see if you have listened...
In pairs, you must answer all the questions and the pair that finishes first with the most answers right will win….