Storm hazards

Question 1

What is a tropical storm?

Answer 1

A tropical storm is an area of low pressure, with strong winds and heavy rainfall.

Diameter = Up to 500km 
Windspeed= Excess of 125kmh

Question 2

Spacial distribution, frequency, and magnitude of tropical storms:

Answer 2

• Occur in tropics between 5 degrees north and south of the equator.
• There is no clear evidence between frequency and intensity increasing as global temperatures increase although the data only goes back to 1944.
  Warmer atmosphere means more evaporation therefore more storms but winds also changing which may prevent storm formation.
• Magnitude measured on the Saffir-Simpson scale from 1-5. Rated by windspeed and storm surge.
• Hurricane return period is the frequency that a certain intensity of hurricane will be expected to return to an area.

Question 3

Causes of tropical storms?

Answer 3

• Formed in the tropics then move north or south of the equator, this is the earth redistributing heat from the tropics towards poles.
• Start as depression (low pressure with rain + wind) which is formed by evaporation from the warm oceans.
• Change to tropical storm due to huge updrafts of air, lower pressure created.

Question 4

What do tropical storms require?

Answer 4

• SST (Sea surface temp) of more than 26 degrees.
• Corolis force from the rotation of the earth spins the storm.
• Warm air rising from the ocean at the equator, hadley cell, causes clouds to form.
• Uniform wind direction at all heights.
• Prevailing wind direction to push storms across the ocean (easterly)
• Energy dissipates as they hit land, as no more evaporation.

Question 5

Contrasting case study, Hurricane Sandy 2012:

Answer 5

October 2012, hurricane Sandy passed through Jamaica, Haiti, Cuba and eventually the east coast of the USA. Met with a weather system from the west in the USA and became an extra-tropical cyclone.

Development index:

• GDP per capita = $52,549
• Life expectancy =79 years
• Infant mortality = 5.6/1000
• Education = 16.5 years

Impacts:

• 233 people killed
• Ruptured gas pipes caused many fires and disrupted road networks along the coast.
• In NY city streets, tunnels, and subway lines were flooded as well as power lost in the city.
• Total cost of the damage was $75 billion.
• $20 billion in insurance cost.

Responses:

• American red cross supplied 4000 volunteers to help affected.
• NY provided emergency supplies of petrol.
• Events in the USA through live telethon and day of giving rose $37 million.
• US gov approved $50 billion relief package.

Question 6

Contrasting case study, Cyclone Winston 2016:

Answer 6

February 2012, Fiji was struck by the strongest tropical storm to hit the southern hemisphere.

Development index:

• GDP per capita = $8620
• Infant mortality = 19.1/1000
• 4% below poverty line
• Education = 15 years

Impacts:

• 44 killed
• 40,000 homes damaged/destroyed
• 250,000 without clean water
• Total damage was $1.4 billion with $54 million to agricultural sector

Responses:

• Provision of shelter, food, water and medicine
• Cleared waste and debris to allow for reconstruction
• US donated $9 million in financial support
• New Zealand and Australia provided financial support under the Franz agreement
• Money and relief also raised by many charities such as the Red Cross and Oxfam