storm hazards Flashcards
how are tropical storms formed
- Hurricanes need a lot of heat to form, which is why they usually occur over tropical seas (at least 27°C).
- The sun is close to the equator, providing energy to heat the ocean.
- The warm ocean heats the air above it causing it to rise rapidly.
- Water evaporates quickly from the hot surface of the ocean, so the rising air contains great amounts of water vapour.
- The rising air starts to spin (anti-clockwise in the northern hemisphere)
- The centre of the storm - the eye - is calm.
- As the air rises it cools, condenses and forms towering cumulonimbus clouds.
- The rapidly rising air creates an area of intense low pressure. The low pressure sucks in air, causing very strong winds.
- they are driven by prevailing winds
- Once the storm moves over land it starts to lose energy and fades.
where do tropical storms occur
they occur between the tropics of Cancer and Capricorn which are 23.5 degrees north and south of the equator
5 hazards associated with tropical storms
-high winds: can travel out 300 km/h+
-average winds are 120km/h
destroy buildings
uproot trees
- storm surges(large rise in sea level): caused by high winds pushing water at high tides towards the coast in low pressure conditions
- heavy rain: caused by warm, moist air as it rises and cools
- flooding: caused by heavy downpour which causes river discharge to increase
-landslides: water infiltrates soil and rock making it less stable
90% of landslides are caused by heavy rainfall each year
short term responses to tropical storms
evacuations
hurricane case study
location
date
category
USA hurricane Sandy
22nd October 2012- 2nd November 2012
category 3
hurricane sandy pattern
- started off the coast of Africa
- travelled north west across the Atlantic ocean through the Caribbean
- reached the east coast of the USA
how are tropical storms measured
- classified using the Saffir-Simpson Scale which is based on wind speed and estimated damage
- 119km/h(category 1)
- category 5 is the strongest and category 1 is the weakest
frequency of tropical storms
- around 100 per year
- some never reach land
- 5.9 become actual storms
- storms in the northern hemisphere occur between june and november
- storms in the southern hemisphere occur between november and april
- tropical storms are irregular
- they can be identified with satellite imagery allowing them to be predicted
- no evidence for increasing frequency or intensity
- 9/10 largest storm have occurred in the last 2 decades
6 social impacts of the hurricane sandy
- 433 deaths in total
- 147 direct deaths
- 72 in the USA
- 54 in Haiti
- 11 in Cuba
- 215 patients evacuated from the New York University Langone Medical Centre due to power failure
- 8.5 million homes and businesses left without power
- supermarkets ran out of essentials in Washington DC
- marathon cancelled resulting in a loss of income
- 32 million forced out of their homes temporarily or permanently
4 economic impacts of the hurricane sandy
- caused $71 billion in damages
- New York’s economic loss of $18 million
- 18,000 flights cancelled
- crops lost resulting in an economic loss for farmers
6 environmental impacts of the hurricane sandy
- shanty towns in Haiti washed away
- fallen trees and floods affected wildlife habitats
- untreated sewage washed into public drinking water
- more than 70% of crops in south Haiti destroyed
- transport infrastructure destroyed
- 10m of beach lost in parts of New Jersey
- winds up to 185km/h
what prior management did the US put in place for hurricane sandy
(4 points)
- the USA national hurricane centre predicted and monitored the hurricane path
- centre issued warnings to local authorities
- police evacuated thousands of people
- President Obama signed for emergency declarations
3 short term responses for hurricane sandy
-local authorities issued warnings
-satellites used to monitor hurricane
-$50.5 billion hurricane sandy relief bill signed by president Obama
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cyclone case study name location date category
cyclone Nargis
bay of Bengal, Myanmar
may 2nd 2008
category 4
cyclone Nargis path
- formed in the bay of bengal in the last week of april 2008
- as it approached Myanmar it strengthened to a category 4
- may 2nd it hit Myanmar with wind speeds of around 215km/h and a storm surge of 5m
7 social impacts of cyclone nargis
- estimated death toll of 138,000
- 50,000 people still missing
- lack of food and water for survivors
- disease outbreak caused more death
- 2.4 million severely effected
- 1,163 temples destroyed
- 1 million+ left homeless
3 economic impacts of cyclone nargis
- $10 billion in damages
- flooding of rice fields cost people their livelihoods and income
- 75% of buildings collapsed
5 environmental impacts of cyclone nargis
- rice fields flooded on the Irrawaddy delta
- 2008 and 2009 harvest destroyed
- strong winds up to 217km/h
- 7.6m storm surge
- flood waters moved 40-50km inland
what prior management did Myanmar put in place for Cyclone Nargis
(3 points)
- no dedicated hurricane monitoring system
- Indian weather agencies warned Myanmar government 48 hours before the cyclone hit
- no emergency plans, evacuations or early warning systems
long term responses to hurricane sandy
3 points
- 2013: New York - rebranding ‘a stronger more resilient new York’ which was a plan to rebuild impacted communities
- USA invested in flood prevention and coastal protection schemes
- August 2013 the Hurricane Sandy Rebuilding Task Force released the report Hurricane Sandy Rebuilding Strategy
how vulnerable was the USA to Hurricane sandy
4 points
- earthquakes and hurricanes had struck before so people had experience
- safe homes program in south Carolina decreases vulnerability for home owners
- in north Carolina houses sat on dunes making them more vulnerable as the dunes eroded
5 short term responses to cyclone Nargis
- initially the government refused international aid
- 7th may aid was accepted
- aid workers were not allowed in until the 19th o may
- U.K gave $17 million in aid and an international relief team
- USA donated $41million and sent help form the red cross
5 ways cyclone Nargis has affected Myanmar
- began collaborating with other countries
- improved national forecasting
- 87% of people have smart phones and receive warnings via an app compared to 3% in 2008
- 2010 citizens were able to vote - country had its first elected leader in 2 decades
- joined Paris agreement on climate change
how has hurricane sandy affected the USA
3 points
- 1 in 5 families had not returned home
- 1/2 of New Jersey residents are unhappy with sate recovery
- 1/3 admit that they now struggle to pay for food, fuel and bills
response and risk management to storm Hazards: prevention
- in current climate and weather conditions tropical storms cannot be avoided
- strategies to mitigate climate change could prevent higher category storms
response and risk management to storm Hazards: preparedness
- awareness via education of what do in the event of a tropical storm
- evacuation plans and training
- satellite image tracking manage areas at risk
- storm warning system and television broadcasts tracking the storm
response and risk management to storm Hazards: mitigation
- search and rescue, emergency aid, evacuation
- strengthening the home with door barricades, roof strengthening
- clearing loose debris before storms.
response and risk management to storm Hazards: adaption
- move away from areas at risk
- design buildings to withstand high winds and flood damage
- flood defenses like houses on stilts, coastal walls, river levees
5 ways Myanmar was vulnerable to cyclone Nargis
- country was suffering from 5 years of internal conflict
- only 2.2% of Myanmar’s GDP went towards healthcare in rural areas
- poor sanitation in rural areas
- 1/4 households live below the poverty line
- deforestation of Mangroves on coastline made the storm surge worse
tropical storm description
- low pressure environments that form between the tropics
- up to 700km in diameter
- eye is calm - sinking air
- eyewall - most destructive
- cloud banks
conditions needed to form tropical storms
- waters at least 27 degrees Celsius - source of heat and water
- ocean depth of at least 50m - provides latent heat
- wind direction needs to be uniform - allows intensity and height to grow
- atmospheric instability
- Coriolis effect/ rotation of earth- doesn’t occur at equator
