Hazards - Tropical Storms Flashcards
What is a tropical storm?
An intense low pressure weather system with winds above 74mph, that can last for days to weeks within the topical regions of our planet
Where do they form?
Between 5 and 30° N or S of the equator
Make landfall on eastern coasts of continents due to the earth’s rotation
What are the key conditions needed for a tropical storm to form?
Sea temps of 27°c or higher to a depth of at least 70m - provides enough heat and moisture for water to evaporate and create a storm
Location at least 5° N or S of the equator - provides strong enough coriolis effect
Low pressure
Low - level convergence of air in atmosphere
What direction do they travel in the northern and southern hemisphere?
Northern - anti-clockwise
Southern - clockwise
How are they formed?
- Atmospheric disturbance over warm seas between 5 and 30° N and S
- Air rises and cools, forming clouds and process of condensation releases latent heat, creating more warming and rising.
- This deepens low pressure area and winds converge as air moves from high to low pressure.
- Due to winds and circles effect the storm starts to spin. Moves over oceans and gathers moist air that rises, realeimg latent heat.
- Storm grows, once wind speed reaches 74mph it is considered a tropical storm.
- Air descends around storm and fuels it more creating a positive feedback loop. When tropical storms reach land they lose energy and friction with land surface causes storm to dissipate.
What are the 5 forms of hazard associated with tropical storms?
Heavy rain, high winds, landslide, river flooding, storm surges
What are the social impacts of hazards?
People killed/ injured
People left homeless and houses destroyed
Flooding causes sewage to overflow, contaminating water supplies.
What are the economic impacts of hazards?
Buildings / infrastructure cost huge amount of money to repair
Businesses damaged so can’t trade
What are the environmental impacts of hazards?
Beaches eroded and coastal habitats destroyed eg) coral reefs
Land polluted by salt water and oil / chemical spills from factories
What are the political impacts of hazards?
People blame authorities for food / water shortages leading to conflict / political unrest
How many storms do tropical oceans generate per year?
Around 80-100
Which ocean generates the highest number of storms?m
Pacific Ocean
When do storms occur in the northern and southern hemisphere?
Majority in summer to autumn as this is when sea temps are at their highest
Northern Hemisphere- July-October
Southern Hemisphere - December-March
What is happening to tropical storm intensity?
Becoming more intense
What has happened to the energy released by the average storm?
It has been calculated that the energy released by the average storm has increased by 70% in the past 30 years.
