Hazards - Tropical storms Flashcards
How many storms are there per year?
45
What is the distribution of tropic stroms? (4)
Eastern Asia - 33%
East Pacific - 17%
West Austrailia - 13%
Caribbean - 11%
What conditions are needed for a tropical storm to form? (4)
1 - Disturbance of the sea surface e.g low pressure
2 - Water that’s 270c for at least 50m -
3 - Convergence of air either within the ITCZ or along the boundary between warm and cold air masses. This causes warm air to rise
4 - A location at least 50 from the equator
Wh don’t tropical storms form 0-50 either side of the equator?
Because the coriolis effect isn’t strong enough to make the strom spin
Why do tropical stoms develop over warm water?
As the evaporation of warm moist water into water vapour releases energy that increases wind speed
Why do tropical stoms form in the tropics?
Because the water here is warm enough
In what locations do tropical storms occur? (4)
1 - Caribbean sea
2 - Bay of Bengal
3 - China sea
4 - Northern Austrailia
What happens when tropical storms move over land and why?
They lose strength because their supply of warm moist air is cut off
What is the coriolis effect?
It is a force caused y the Earth’s rotation. It deflects the path of winds but it’s weak at the Equator
What is the general pattern of movement of tropical storms? (2)
1 - Initially move westwards due to easterly winds in the tropics
2 - They move away from the equator because of the coriolis effect
What are the key features of a tropical storm? (3)
1 - Circular in shape
2 - 100’s km wide
3 - Last 7-14 days
What direction do tropical storms spin in the Northern hemisphere?
Anticlockwise
What direction do tropical storms spin in the southern hemisphere?
Clockwise
What is the centre of the storm called and what is a key fetaure of this?
An area of very low pressure called the eye
What causes strong winds in the tropical storm?
Rising air spiraling around the eye in the eyewall
What extends for a long distance either side of the eye and why? (2)
1 - Cloud cover
2 - Because near the top of the storm there is an outflow of moist air
How are storms classified?
Using the Saddir-Simpson scale
What is the Saffir-Simpson scale based on?
Wind speed
What is the scale for the Saffir-Simpson scale?
Category 5 -1
(strongest-Weakest)
What can the Saffir-Simpson scale estimate?
How much damage a strom will cause
Are tropical stroms frequent and why isn’t this a major issue? (2)
1 - Yes, roughly 100 per year
2 - However some never reach land so don’t develop into a major hazard
Where and When are tropical stroms most frequent? (2)
1 - Northern hemisphere: June - Nov
2 - Southern hemisphere: Nov - Apr
How can the path of tropical storm be predicted?
1 - Certain cloud formations in tropical areas can be identified from satellite imagery - used to tell when a tropical storm is forming
2 - The storm can be trcaked using satellite imagery and models - used to tell when and where it is likely to hit land
What is the effect of high wind speeds in tropical storms? (3)
1 - Destroy buildings
2 - Uproot trees
3 - Carry debris long distances before smashing them into other objects
What wind speeds on the ground can tropical stomrs reach?
More than 300km/h
What is a storm surge? (2)
A large rise in sea level caused by:
1) High winds pushing water towards the coast
2) The low pressure of a storm
What is an example of heavy rainfall caused by a tropical storm?
Denise - 1966:
1000mm rain felll in 12 hrs at La Reunion
What are the effects of heavy rainfall from a strom surge? (2)
1 - Flooding
2 - Landlsides - water infiltrates soil and rock making it less stable
What are the 5 storms hazards?
1 - High winds
2 - Storm surges
3 - Heavy rain
4 - Flooding
5 - Landslides
What are the social impacts of storm surges? (5)
1 - Debris carried in flood water - kill people
2 - Destroyed houses - homelessness
3 - Electricity cables damaged + Cut off supplies
4 - Flooding results in sewage overflows contaminating water - spread disease
5 - Damage to agricultural land - food shortages
What are the political impacts of storm surges? (2)
1 - People may blame the authorities for food shortages / lack clean water - leading to conflict and political unrest
2 - Repairing damages - stunt development
What are the economic impacts of strom surges? (3)
1 - Repairing infrastructure costly
2 - Damaged business can’t trade
3 - Agricultutal land damged - less farming
What are the environmental impacts of storm surges? (4)
1 - Beached eroded
2 - Coastal habitats damaged
3 - Sediment depositied in aquatic ecosystems may damage fish breeding grounds
4 - Environments polluted by chemicals and oil spilled from damaged factories
What are long term responses to a storm surge? (5)
1 - Don’t build new developments in high risk areas
2 - Governments can plan evacuation routes
3 - Educate people on how to prepare for a storm
4 - Offer disaster training to emergency services
5 - Buidling flood defences along rivers and coasts
How can infastructure be developed to withstand a tropical storm? (3)
1 - Using reinforced concrete
2 - Securly fixing roofs
3 - Building infrastructure on stilts
What are the short term responses to a storm surge?
Evacuating people from high risk areas
