W & C GW3 Flashcards
Characteristics of tropical cyclones
1. ?
Strong Winds
strong winds of at least 119km/h
low atm pressure above warm oceanic surface in centre of cyclone -> steep pressure gradient -> strong winds moving inwards and upwards at high speeds -> column of sinking air = eye
Characteristics of tropical cyclones
2. ?
Low Central Pressure -> eye
moist air over ocean expands and rises -> condensation -> releases latent heat = heat energy released when waer vapour condenses into water droplets
continuous and large scale release of latent heat warms air, cauding air to expand and rise further -> reduces air pressure near ocean surface -> creating and sustainging area of low pressure in centre
air cools and sinks -> descending air creates environemnt at centre -> calmness and absense of clouds -> eye
Where are tropical cyclones found?
- (1)
- (2)
- Between latitudes of 8° and 15° north and south of Equator
- Conditions
High ocean surface temp above 26.5°C
Coriolis effect
Where are tropical cyclones found?
Conditions
1. ?
High ocean surface temp above 26.5°C
heat and moisture from ocean water needed to form -> sustain energy
Where are tropical cyclones found?
Conditions
2) ?
Coriolis Effect
Northern hemisphere -> deflects winds to right -> acw
Southern hemisphere -> deflect winds to left -> cw
Hazards associated with tropical cyclones
3
- Storm surges
- Strong Winds
- Torrential rainfall
Hazards associated with tropical cyclones
1. ?
P: Storm Surges
E: low air pressure and strong winds -> tropical cyclones form over warm ocean water -> intense low pressure in eye cause sea level to rise -> strong winds -> huge waves -> sudden rise of sea level, pile up against coastline beyond normal high tide
E: In Texas 2008, Hurricane lke caused a storm surge of 4-6 metres above normal tide -> property damage US$24.9 billion
Hazards associated with tropical cyclones
2. ?
P: Strong Winds
E: strong winds -> loose debris to fly and hit people and buildings -> damage infrastructure, injure people
E: Hurricane Andrew in 1992, strong winds up to 177km/h -> damage to Bahamas and various parts of US -> disrupted power supply of 150 000 homes
Hazards associated with tropical cyclones
3. ?
P: Torrential rain
Ex 1: large amounts of rainfall -> inland flooding, overflow rivers and streams
Eg 1: Hurricane Isabel 2003 flooded rivers -> flood Virginia, Washington DC -> area about 120 times of SG -> damage of more than US$2.23 billion
Ex 2: rainfall -> too much water in soil -> soil unstable -> landslide -> remove and crush buildings
Impacts of tropical cyclones
3
- Physical
- Economic
- Social
Impacts of tropical cyclones
1. ?
P: Physical impact
E: damage to infrastructure (buildings, bridges, roads) -> difficult to transport food, clean water, medicine to areas that need these items, communication networks also disrupted
E: Typhoon Ketsuna in 2009 -> damage road network in Philippines, Cambodia and Laos -> hindered rescue work -> 80% of healthcare centres in Manila, Philipines destroyed -> difficult to distribute food and medicine
Impacts of tropical cyclones
2. ?
P: Economic Impact
Ex 1: costs of repair of damaged property and infrastructure
Eg 1: damage caused by Hurricane Katrina in 2005 cost US$81 billion, large portion of cost came from repairs of more than 200,000 homes
Ex 2: damaged crops -> loss of income
Eg 2: Tropical Cyclone Yasi in Northern Queensland, Australia in 2011, 75% of banana crops that cost about US$350 million was lost
20% of area of sugarcane farmland destroyed, farmers suffering economic losses
Ex 3: Food aid needs to be provided to victims as crops are destroyed -> however, flooded roads make it difficult to let people from affected areas to access to food aid -> $$ needed to repair roads to provide aid
Eg 3: Cyclone Nargia 2008 in Myanmar, US$4 billion needed to repair infrastructure and to provide humanitarian aid
Impacts of tropical cyclones
3. ?
P: Social impacts
P 1: disruption to water supply, sanitation, hygiene facilities, water-borne diseases
Ex 1: flooding -> sewage from burst sewage pipes to flow into existing water supplies -> contaminate them -> spread of water-borne diseases (cholera, typhoid fever)
Eg 1: Cyclone Aila 2009 in West Bengal India, contaminated drinking water -> cholera outbreak 1000 infected people and 14 deaths
P 2: spread of diseases
Ex 2: flooding -> stagnant water -> increase spread of diseases
Eg 2: Hurricane Mitch in 1998 increases dengue fever and malaria cases in Guatemala and Nicaragua -> large-scale flood, diseases spread at fast rate -> difficult to provide proper medical care
P 3: displacement of people from their homes
Ex 3: houses destroyed during hurricane -> lost homes, no place to stay
Eg 3: Hurricane Katrina in 2005 in New Orleans, US, hundreds of thousands of people lost their homes -> victims lived in temporary shelters
How ppl respond to tropical cyclones?
- (3)
- Emergency action
2. Mitigation measures (3)
How ppl respond to tropical cyclones?
1. ?
Emergency action
- involves taking immediate action in response to nay situation that poses risk to people’s health and lives
- protect lives and properties
- national government: repair damage
- non-governmental organisations: provide basic necessities
Eg) Red Cross is a non-governmental organisation provide victims with basic necessities such as food, clothing, shelter and healthcare when Typhoon Megi hit the Philippines in 2010
How ppl respond to tropical cyclones?
Mitigation measure
1. ?
Prediction and warning
Prediction 1:
- analyse long-term climate records
- establishes the pattern of the occurences and the severity of the damage caused by past cyclones
Prediction 2:
- predictions to be made about cyclone’s path to detect areas that may be affected and the degree of damage
- based on weather information
Warning 1:
- warning systems for tropical cyclones, announced to public through these warning systems
- people can be warned and evacuated in time
How ppl respond to tropical cyclones?
Mitigation measure
2. ?
(2)
Land use control
- regulate the use of the land by placing restrictions on how the land can be used
(1) : Coastal plain management
- Developers may need to pay higher taxes to use the land along the coasts, discourage development to be built on vulnerable areas
- Protected zones where no development can take place can also be allocated
( - ) this measure is only successful when authorities are able to enforce them
( - ) land use controls require much time and manpower
( - ) residents reluctant to move
(2) : Flood plain management
- mapping the land use of an area
- ensure new developments in floodplains are not prone to floods
- reduce potential of flood damage in already developed floodplains
- during actual flood, people can leave flooded area quickly
( - ) actual flood can be worse, may be other areas that flood
How ppl respond to tropical cyclones?
Mitigation measure
3. ?
Reducing vulnerability of infrastructure
- infrastructure need withstand tropical cyclones
reducing vulnerability of infrastructure include:
- resistant to wind and water
- regular inspection of river embankments
- locating utility lines underground
Eg) Florida, USA, designs of roof and openings of houses are improved
( + ) those houses suffered only from minor roof damage when Hurricane Wilma struck in 2005
protective barrier
( + ) prevent river from overflowing
Eg) coast in Samoa, minor damage made when Cyclone Val struck because of protective barrier
( - ) expensive
