Tropical Storms

• The rising air cools and condenses into clouds which form thunderstorms
• A tropical storm is formed when warm, moist air rises from the ocean surface
• Tropical cyclones


  large scale rotating storms that form over oceans in tropical areas
• Eye of a storm


  Centre of a storm
• A tropical cyclone is a very large, spinning storm that forms in the tropics.
• Tropical cyclones have high winds and torrential rain, and usually affect small islands and coastal regions.
• Tropical cyclones are characterised by their low pressure, intense weather and spinning structure.
• Warm air rises and creates an updraught during the formation of a tropical cyclone, causing an area of low pressure to form.
• The area inside a tropical cyclone is often as low as 950mb
• The eye can be 15% lower pressure than areas outside of the storm.
• Tropical cyclones are characterised by thunderstorms, strong winds and intense rainfall.
• The eyewall contains the strongest winds, thunder and lightning, and torrential rain.
• In very intense storms, sustained winds can reach 240km/hour, and gusts can exceed 320km/hour
• Tropical cyclones rotate due to the spin of the Earth
• In the southern hemisphere the storms spin clockwise and in the northern, anticlockwise
• Hurricane: In the USA and Latin America/ The Caribbean. Usually form mid-July to September.

   
• Cyclone: Australia (Oceania) and Madagascar. Usually form January - April (summer- autumn in the Southern Hemisphere).
• Where do Tropical Cyclones Develop?

  Tropical cyclones need very specific conditions to form, so will only form in certain areas. Tropical cyclones form between 5-15° north or south of the equator, in warm oceans.
• The location that a tropical cyclone forms in is known as its source area.
• Temperature for tropical cyclone to develop

  Ocean temperatures must be around 26 - 27°C and at least 50 metres deep. Warm water provides the storm with energy. This is why storms form during late summer, when the ocean has had time to heat up.
• Wind shear for tropical cyclone to develop

  Winds must be present for the swirling motion to form, but not too strong or the storm system will be ripped apart in the early stages.
• Air pressure for tropical cyclone to develop

  Must be in areas of unstable air pressure - usually where areas of high pressure and low pressure meet - so that warm air rises more readily and clouds can form. Warm air rises because it is less dense than cold air.
• Rotation for tropical cyclone to develop

  Tropical cyclones only form around the equator, between 5-15° either side of the equator, but tropical cyclones will not form on the equator.
• The Coriolis Effect is the effect of the Earth's rotation on weather events.
• The storm spins because the Earth is spinning; but there is no Coriolis Effect at the equator, hence why these storms will only form a certain distance away from it.
• Tropical cyclones follow certain pathways that are driven by global wind circulation.
• It is possible to follow the track of a tropical cyclone using satellite imagery, as the storms are so large they can be seen from space.
• cyclone structure

  
• Tropical cyclones can be very damaging to people, the environment, and the economy.
• High winds - strong enough to lift roofs and bring down infrastructure, which can be very dangerous if they hit someone
• Intense rainfall - over 100cm of rain can fall in a single storm event
• Storm surges - when the storm passes over the coast, it picks up a lot of water and causes an abnormally high tide called a storm surge. These can be anywhere from a couple of feet to tens of feet high.
• Coastal flooding - storm surges cause flooding on the coast, which can damage coastal infrastructure and contaminate near freshwater.
• Landslides - the large amount of rainfall as well as coastal flooding can oversaturate the ground and trigger landslides.
• Some people are less educated on tropical cyclones, so they could be unprepared.
• Being aware of evacuation routes and being prepared (e.g. having an emergency kit with first aid, food supplies, a whistle etc.) makes people less vulnerable.
• Poorer countries may not be able to respond to a tropical cyclone as effectively as a wealthier country.

   
• Emergency services require a lot of money. Poorer countries often rely on international aid to help them recovers.
• Sea level rise caused by climate change could make people more vulnerable to storm surges as the sea will be higher.
• Climate change also affects intensity of tropical cyclones and could affect the distribution in the future, potentially making more people vulnerable.