Tropical Cyclones (1) Flashcards
What are Tropical Cyclones?
Intense low-pressure systems either heavy rain and strong winds that spiral at the centre
When do Tropical Cyclones develop?
When sea temperatures are at 26.5C or higher
When the wind shear (difference in wind speed) between high and low parts of the atmosphere is low
Where is the source area for most Tropical Cyclones?
Between 5 and 30 degrees north and south of the equator
- isn’t warm enough elsewhere
How do Tropical Cyclones form?
(1) Warm, moist air rises and condensation occurs, releasing large amounts of energy, increasing the storm’s power. Rising air creates an area of low pressure, increasing surface winds
(2) The Earth’s rotation deflects the path of the winds, causing the cyclone to spin
(3) Tropical cyclones move towards the west due to easterly winds near the equator
(4) Cyclones intensify due to the energy from the warm water
(5) They dissipate when they move over land or cooler water - lose energy from warm water
How can Climate Change affect Tropical Cyclones?
Can cause the source areas to change. If sea temperatures rise, more oceans could be above 26.5C, meaning more places in the world could experience tropical cyclones
Features of ‘the Eye’ in the Tropical Cyclone
The ‘eye’ is the centre of the cyclone - up to 50km across and caused by descending air
Very low pressure, light winds, no clouds, no rain and high temperatures
Describe the feature of a Tropical Cyclone surrounding the ‘eye’
The ‘eye’ is surrounded by the ‘eyewall’
Spiralling rising air, very strong winds, storm clouds, torrential rain and low temperatures
What happens to the storm towards the edges of the Cyclone?
Wind speeds fall, clouds become smaller and more scattered, rain is less intense and temperatures increase
Name some Physical hazards caused by Tropical Cyclones
- High winds: wind speeds can reach 250km/h
- Intense rainfall: can release trillions of litres of water per day as rain
- Storm surges: large rise in sea level caused by low pressure and high winds
- Coastal flooding: happens as a result of storm surges and strong winds driving waves
- Landslides: heavy rain makes the cliffs unstable
Name some ways in which the Physical hazards have an impact on people
- People may drown in strong currents created by storm surges
- Wind speeds can be strong enough to destroy buildings - homelessness
- Floodwater can carry large amounts of debris - killing/injuring people
- Electricity supplies are cut off
- Flooding causes sewage overflows - contaminates water supplies + diseases
- Unemployment
- Food shortages - damaged crops / livestock killed
Name some ways in which the Physical hazards have an impact on the Environment
- Trees are uprooted by high winds - damages woodland habitats
- Storm surges can erode beaches and damage coastal habitats
- Flooding caused by storm surges can pollute freshwater environments with saltwater
- Landslides deposit sediment in rivers and lakes - kills fish and other wildlife
- Damage industrial buildings on the coast - oil spills, chemical leakages are damaging
Examples of Physical Vulnerability for countries
(1) Low-lying coastlines are vulnerable to storm surge flooding
(2) Steep hillsides may increase the risk of landslides
Examples of Economic Vulnerability for countries
(1) Many people depend on agriculture which is often badly affected
(2) People may not have insurance to cover the costs of repairing damage
- Economic damage is greater in developed countries as infrastructure is worth a lot of money
Examples of Social Vulnerability for countries (mainly developing)
(1) Poor quality buildings are more easily damaged
(2) Health care may not be good - struggle to treat casualties
(3) Harder to rescue people due to poor infrastructure
(4) Little money for training emergency services / flood defences
Name the strategies to Prepare and Respond to Tropical Cyclones
Forecasting
Evacuation
Defences
Describe Forecasting in Preparing for Tropical Cyclones
- Scientists can use weather forecasting and satellite technology to monitor cyclones to predict paths
- The cyclone’s magnitude can be monitored by measuring its wind speeds
- Predicting when cyclones will hit gives people more time to evacuate and protect their homes
Describe Evacuation in Responding to Tropical Cyclones
- Governments can plan evacuation routes to make the process more efficient (eg signposts)
- Successful evacuations reduce the number of deaths and injuries
- Emergency services can train and prepare for disasters, reducing the number of people killed
Describe Defences in Preparing for Tropical Cyclones
- Defences (eg sea walls) can be built along the coast to prevent damage from storm surges
- Buildings can also be built to withstand a storm surge
- Reduces the number of destroyed buildings, saving lives and reducing the levels of homelessness
Explain the seasonal distribution of Tropical Cyclones in the Northern Hemisphere
Majority of cyclones occur from June - November as sea temperatures are highest
Explain how the global circulation of the atmosphere affects the track of Tropical Cyclones
Easterly winds near the equator cause cyclones to move west.
As they travel further from the equator, their path may start to curve east due to mid-latitude westerlies
When do most of the Tropical Cyclones occur in the Southern Hemisphere?
November - April
