Tropical storms

What are tropical storms?

Intense low pressure weather systems that develop in the tropics

What temperature does the ocean need to be for a tropical storm to form?

26-27 degrees or more

Why does the ocean need to be warm for a tropical storm to form?

Warm water provides the storm with energy

How deep does the ocean need to be for a tropical storm to form?

more than 70m

What location are tropical storms usually created at?

A location 5° north or south of the equator

Why are tropical storms formed a certain distance from the equator?

So the Coriolis force brings about maximum rotation

Why are no tropical storms found directly on the equator?

The Coriolis effect is too weak

What causes the spin of a tropical storm?

Coriolis effect

What is the Coriolis Effect?

The effect of Earth's rotation on the direction of winds and currents.

What air pressure is needed to form tropical storms?

Must be in areas of unstable air pressure- usually where areas of high pressure and low pressure convergence

What is wind shear?

change in wind speed or direction with height

What wind shear is needed for tropical storms to form?

Low

What is the sequence of formation of a tropical storm?

Warm ocean water causes lots of evaporation.

• Winds push moist air upwards.

• The rising air is unstable and rises quickly.

• The moisture condenses into clouds and rain, releasing heat that makes the air rise even faster.

• Cooler air from above sinks down to replace the rising air.

How are tropical storms distributed?

Tropical storms form between 5-15°N and 5-15°S of the equator and move outwards through the tropics

When do tropical storms die out?

when they reach land or when they begin to move over colder water

What is the main form of measurement of tropical storms?

The Saffir-Simpson scale

What does the Saffir-Simpson scale go from?

1-5 (1=minimal damage, 5=catastrophic damage)

What is the Saffir-Simpson scale based on?

pressure at the centre, wind speed, storm surge and damage potential

Give an example of a category 5 hurricane

Hurricane Andrew 1992 - 65 Dead , 250,00 Homeless, £2.7.3 BN Damage

How many tropical storms develop each year?

around 80-100

How will the intensity of tropical storms change due to climate change?

Expected to get between 2 and 11% more intense by 2100. This will mean more category 4 and 5 storms, leading to greater levels of destruction along tropical coastlines.

How will the distribution of tropical storms change due to climate change?

The source areas of tropical storms may extend further north and south of the equator, beyond the tropics (latitudes 23 N/S)

How will the frequency of tropical storms change due to climate change?

ANOMALY. The number of tropical storms is expected to stay the same - only the strength and location of them will change.

What do the impacts of tropical storms depend on?

- storm intensity

- speed of movement

- distance from the sea

- preparation of the community

- warnings and community response

What are the hazards created by tropical storms?

- high winds

- storm surges

- very heavy rainfall

Winds often exceed ____km/hr and over ____km/hr in a category 5 hurricane.

150, 250

High winds cause damage to...

buildings, structures, bridges and powerlines.

Winds pick up...

debris, further damaging structures when crashing into them

What is a storm surge?

A temporary, localized rise in sea level as a result of atmospheric pressure changes and storm wind direction.

Outline the physical causes of a storm surge

Low pressure systems combined with a high tide and strong onshore winds

Give an example of how topography can play a part in storm surges

Bays can have a funnelling effect

What percentage of deaths from hurricanes are caused by storm surges?

90%

How does heavy rainfall play a hazard in tropical storms?

•Rainfall can exceed 200 to 300mm, bringing severe flooding

Which can later cause landslides and mudslides

How can tropical storms be predicted?

Scientists use data from things like radar, satellites and aircrafts to monitor storms. Computer models are then used to calculate a predicted path for the storm.

What are five social impact of tropical storms?

- Deaths from drowning or debris, and injury.

- Sewage overflows can contaminate water supply - spreading diseases.

- Agricultural land can be destroyed, leading to food shortages.

- Destruction of homes leave people homeless.

- Electricity supply cuts out, so people cannot communicate / co-ordinate a rescue.

What are three economic impacts of tropical storms?

- Repairing and rebuilding infrastructure can be very costly.

- Businesses can be destroyed, leaving people without a job.

- Agricultural land being damaged affects commercial farming.

What are four environmental impacts of tropical storms?

- Freshwater ponds can be salinised, leaving people without a key water source. (e.g Myanmar).

- Beaches and coastal habitats are eroded (e.g coral reefs).

- Pollution from oil spills after oil rigs are destroyed.

- Landslides can block rivers, changing their course.

What are two political impacts of tropical storms?

- Authorities blamed for food/water/energy shortages can cause conflict, political unrest.

- Spending on repairs limits spending elsewhere, e.g on development.

What is the threshold for a tropical storm to be be called as such?

Wind speeds of 74mph

What did the Bhola Cyclone of 1970 lead to?

Political unrest in Pakistan leading to independence of Bangladesh

What was the most significant impact of the Bhola Cyclone of 1970?

500,000 deaths

What was the most significant hazard of the Bhola Cyclone of 1970?

Storm surge over low-lying area

What was the most significant hazard of Hurricane Katrina in 2005?

Flooding due to failure of levees

What were the most significant impacts of Hurricane Katrina in 2005?

$125 billion in damages

80% of New Orleans underwater

What did Hurricane Katrina lead to?

Sparked discussions over climate resilience and disaster management