Tropical Storms

Question 1

What other names are tropical storms known by?

Answer 1

Cyclones (India)
Hurricanes (North Atlantic)
Typhoon (South-east Asia)

Question 2

How fast must the wind in a tropical storm be at a minimum?

Answer 2

A tropical storm must have average wind speeds in excess of 75mph (120kmph)

Question 3

Describe some characteristics of tropical storms

Answer 3

Have a degree of symmetry around the eye
Most powerful part is the eye wall, the bank of cloud that rings around the eye
Cloud and rain extend in a series of waves well beyond the eye wall
Tornadoes are often formed
Highly localised nature makes then hard to predict
Highly destructive

Question 4

Describe the distribution of tropical storms

Answer 4

Vast majority are formed around the tropics, though some extend beyond this region
They do not occur at the equator or around South America

Question 5

What factors are involved in the formation of tropical storms?

Answer 5

Form and develop over oceans
Sea temperatures over 26°C (often in summer)
Atmospheric instability, where warm air is being forced to rise
Rotation of the earth (coriolis effect) to create spinning motion
Uniform wind direction at all levels, otherwise it is destroyed before it can form

Question 6

How do tropical storms form?

Answer 6

Develops clearly defined rotation
Warm, moist air rises rapidly in centre, and is replaced by air drawn in at the surface
Central vortex develops as more and more air is drawn in and rises
Eye is characterised by collum of dry sinking air
As air rises, it cools, condenses and forms towering cumulonimbus clouds
Sometimes a number of isolated thunderstorms coalesce to form a single giant storm
When condensation occurs, latent heat is released, which powers the storm
Prevailing winds cause it to grow, and is reinvigorated by ocean
Starts to decay when it reaches land (essentially out of fuel)

Question 7

What are the hazards associated with tropical storms?

Answer 7

Strong winds
Storm surges
Coastal and river flooding
Landslides

Question 8

Why are strong winds a hazard?

Answer 8

Capable of causing significant damage and disruption by tearing off roofs, breaking windows and damaging communication networks
Debris forms flying missiles whisked up by the wind
Damaged power lines lead to widespread electricity cuts and occasionally fires
Debris strewn over roads can cause transport disruption

Question 9

What makes storm surges a hazard?

Answer 9

Surge of high water which sweeps inland from the sea, flooding low-lying areas
Caused by a combination of low atmospheric pressure of tropical storm, enabling sea to rise vertically, and powerful surface winds
Are a major cause of widespread devastation and loss of life

Question 10

What makes coastal and river flooding a hazard?

Answer 10

The warm, humid air associated with a tropical storm can generate torrential rainfall, often in excess of 200mm in just a few hours → flash flooding
Urbanisation has exacerbated flood hazard

Question 11

What makes landslides a hazard?

Answer 11

Estimated that up to 90% of landslides each year are caused by heavy rainfall, and many are triggered by tropical storms
Intense rainfall increases hydrostatic pressure within a slope, which weakens cohesion and triggers slope failure

Question 12

What scale are tropical storms measured on?

Answer 12

Saffir-Simpson scale
Five categories, with 5 being worst
Needs winds over 75mph to get into category 1
Needs winds over 156mph to get into category 5

Question 13

How can you prepare for tropical storms?

Answer 13

Education, public awareness campaigns - posters, radio, TV - warn people of dangers and provide instructions
Stronger doors and windows, emergency supplies, evacuation routes, insurance against storm damage, cyclone shelters
Satellites and other technology to track tropical storms and predict path and issue warnings

Question 14

How can you mitigate effects of tropical storms?

Answer 14

Soft engineering → planting trees, building up beaches
Hard engineering →sea walls, levees
Coral reefs act as buffer
Programmes that grant money so homeowners can make property more resilient
Disaster aid: both immediate humanitarian aid (search and rescue, food, water, medicine, shelter) and longer term reconstructional aid
Insurance to protect against storm damages (huge social issues as rich can afford high premiums)

Question 15

Can tropical storms be prevented?

Answer 15

Tropical storms cannot be prevented, instead the effects can only be mitigated

Question 16

How do people adapt to tropical storms?

Answer 16

Land-use zoning aims to reduce vulnerability of people at coast →low value land uses occupy coastal strip
Coastal properties on stilts, and non-residential functions on ground floor (garage or storage area)