Transcript L7 Tropical Revolving Stormsx

Tropical Revolving Storms
Tropical Revolving Storms Form Over Warm Water in the Tropics
1) Tropical revolving storms are huge spinning storms with strong winds and torrential rain.
2) They develop over warm water. As warm, moist air raises and condenses, it releases energy that increases wind
speed.
3) Scientists don’t know exactly how they are formed but they do know the conditions needed. These include:
• A disturbance near the sea-surface that triggers the storm (e.g. an area of low pressure).
• Sea water that’s warm (above 26.5°C to at least 50m below the surface), so lots of water will evaporate.
• Convergence of air in the lower atmosphere – either within the ITCZ or along the boundary between warm
and cold air masses. This forces warm air to rise.
• A location at least 5° from the equator. They don’t form 0-5° either side of the equator because the coriolis
effect isn’t strong enough to make them spin.
4) So tropical revolving storms form in the tropics because the water there is warm enough.
5) They occur in the Caribbean Sea (where they are called hurricanes), in the Bay of Bengal (where they are called
cyclones), in the China Sea (where they are called typhoons) and in North Australia (where they are called willywillies).
6) Tropical revolving storms lose strength when they move over land because their supply of warm, moist air is cut
off.
7) They initially move westwards due to the easterly winds in the tropics, e.g. the trade winds move cyclones west
across the Atlantic Ocean.
8) They move away from the equator because of the coriolis effect.
Tropical Revolving Storms Have a Lot of Impacts
The strong winds, high rainfall and storm surges that come with tropical storms can cause havoc. High
rainfall and storm surges cause flooding ( and heavy rain can make hills unstable, causing landslides).
Here are a few examples of the possible impacts of these things:
Environmental Impacts
1) Beaches are eroded and coastal habitats
(e.g. coral reefs) are damaged.
2) Environments are polluted by all sorts of
things, e.g. salt water, oil, chemicals
spilled from factories damaged by the
storm.
Economic Impacts
1) Buildings, bridges, roads, railways,
ports and airports are damaged or
destroyed. These cost a huge
amount to rebuild.
2) Business premises are damaged or
destroyed, so they can’t trade.
3) Agricultural land is damaged,
affecting commercial farming.
Social Impacts
1) People may drown, or be injured or killed by debris that’s
blown around or carried in flood water.
2) People are left homeless.
3) Electricity supplies are cut off because cables are damaged.
4) Flooding causes sewage overflows which contaminate water
supplies.
5) The shortage of clean water and lack of proper sanitation
makes it easier for diseases to spread.
6) In poorer countries there is often a shortage of food
because crops are damaged and livestock is killed.
7) Unemployment increases because business are damaged or
destroyed.
8) Damaged roads make it very difficult for aid and emergency
vehicles to get through.
The Impacts are Usually Higher in Less Developed Countries
There are several reasons why the impacts of a tropical storm are higher in less
developed countries:
• They don’t have the money to respond, e.g. there is little money for flood defences
or training emergency teams.
• The buildings are poorer quality compared to more developed countries, so are more
easily damaged by storms.
• Evacuation can be difficult to organise, particularly when there is limited access to
transport or when rural populations live in remote areas with poor communications.
• Health care isn’t as good in less developed countries, so they struggle to treat large
numbers of causalities.
• Many people depend on agriculture in less developed countries, which is often badly
affected.
• Infrastructure is often poorer, making it more difficult for emergency services to
reach affected areas.
However, the economic impact is often higher in more developed countries, as the
buildings and infrastructure damaged are worth a lot more money.
The Main Responses to Tropical Revolving Storms
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Evacuation
Planning and education
Building techniques
Aid
Exam question
Describe the characteristics of tropical revolving
storms (7 marks)
Comment on the effectiveness of responses to tropical
revolving storms (8 marks)