Storm hazards

Question 1

What is a tropical storm?

Answer 1

Tropical storms are intense low pressure systems (below 950mb)

Question 2

What are the different names of storms?

Answer 2

Cyclones - Indian oceand and the South Pacific
Hurricanes - North Alantic
Typhoons - Western Pacific and South East Asia

Question 3

Where do tropicla storms form?

Answer 3

• Form over tropical waters between the tropics of cancer and the capricorn but not directly over the equator (5-20 degrees N and S)
• Sea temperatures of 26.5 degrees
• Typically occur between the months of June to November in northen hemisphere and november to april in southern hemisphere
• Natural events excabertaed by climate change
• Key purpose is to redistribute heat from tropics towards the poles and without them global climate change would be very different
• On average kil around 10,000 people a year mostly in coastal areas

Question 4

What are the characteristics of tropical storms?

Answer 4

• Revolving
• 500km in diameter on average and can cause extensive damage and loss of life
• Must exceed average wind speeds of 120km p/h
• Contains a central eye wind speed reduced here
• Most powerful part of the storm is the eye wall with strong winds
• Clouds and tall and wide cumlonimbus
• Rising moist air above oceans combine with cooling dry air from stratosphere
• Torndaedoes may occur within tropical storm
• High rainfall
• Lasts 7-14 days on average
• Path known as track

Question 5

W

What is the spatial distribution?

Answer 5

• Vast majority in the tropics e.g. china,Japan, eastern seaboard of USA

Question 6

Factors that affect the spatial distribution?

Answer 6

Oceans
Ocean temperatures
Atmospheric instability
Corolis effect
wind shear at high altitudes

Question 7

Ocean temperatures

Answer 7

• A sea surface temp in excess of 26 degrees is required for tropical storm formation
• Formed in low altitudes during summer when temps arent at their highest
• Provide energy to the storm through high rates of evaporation and condensation

Question 8

Atmosphereic instability

Answer 8

• Tropical storms most likley to form here where warm air is being forced to rise
• The ITCZ where two limbs of the hadley cell converge to form low pressure on the ground perfect for tropical storms

Question 9

Coriolis effect

Answer 9

• The rotation of the air causes the air to move around the centre of the eye in cicurlar or rotating motion
• This increases with distance away from equator - n-s 5-20 degrees

Question 10

Wind shear

Answer 10

• Winds from diff altitudes prevent tropical storm from attaining heigh and intensity - vertical development ‘sheared off; by multi directional winds

Question 11

The formation of Tropical storms

Answer 11

• Warm moist air rises to be replaced by air drawn in at the surface
• Central vortex as more air is drawn in and rises
• Very centre of the storm (eye) characterised by a column of dry,sinking air
• As air rises rapidly cools condensation and formation of towering cumulonimbus clouds
• Sometimes no of isolated thunderstorms will coalese to form a single giant storm
• Latent heat during condensation powers the storm
• Continues to grow +develop as driven by prevailing winda across oceans when reaches land - supply of energy and water is cut off strom decays and moves back over oceans it reinvigorates

Question 12

What hazards are associated with tropical storms?

Answer 12

Strong winds
Storm surges
Coastal and river flooding
Landslides

Question 13

Strong winds

Answer 13

• Average wind speeds in excesss of 120km p/h (75mph) gusts over 25km p/h in the eye wall
• Strong winds are capable of causing significant damage and disrutpion - teraing off roofs, breaking windows, damaging communication networks
• Debris form flying missiles whisked up by the wind
• Widespread electricity cuts (power outrages) - fires
• Debris over roads can cause major transport disruptions

Question 14

Storm surges

Answer 14

• Surge of high water, typically about 3m in heigh sweep inlanf from sea flooding low lying areas
• Caused by the intense low atmosphereic presssure of the storm (enables sea level to rise vertically) together with powerful driving surface winds
• Storm surges account for 90% of tropical storm deaths
• 1mb drop in air pressure = 1cm rise in water levels
• Inundate agricultural land with saltwater and debris, pollute freshwater supplies and destroy housing and infrastructure
• Contaminated flooding - chlorea
• Enhanced coastal erosion - undermiing buildings and highways
• Looting of shops
• Silting
• Salinisation
• Storm tide

Question 15

Coastal and river flooding

Answer 15

• Warms humid air generates torrential rainfall often in excess of 200mm in a few hours - triggers flash flooding at the coast (in urban areas where surface water can overwhelm the drainage system
• Urbanisation (drains, high density of buildings) exacerbates the flood hazard by encouraging rapid overland flow and causing flash flooding
• As ts moves inland gradually weakens as moisture and energy supply is cut off may still have significant river flooding due to intensity and sheer quantity of rain on the river basin

Question 16

Landslides

Answer 16

• 90% each year caused by heavy rainfall - triggered by tropical storms
• Intense rainfall increases pore water pressure (hydrostic pressure within a slope) which weakens coheison and triggers slope failturw
• Additional weight of water exacerbates problem - 1998 hurricane
• Load release caused by tropical storm induced landslides may tigger eqs in tectonically stressed regions

Question 17

Oceans

Answer 17

• Tropical storms derieve their moisture (through transfer process of evaporation) and energy (in the form of latent heat) from oceans links to the water cycle
• Use the moisture for the formation of clouds and precipitation
• Storms die over land when their energy disspates

Question 18

Eastern asia average

Answer 18

33%

Question 19

Eastern pacific average

Answer 19

17%

Question 20

Indian ocean average

Answer 20

12%

Question 20

Carribbean /gulf of mexico average

Answer 20

12%

Question 21

Madagascar

Answer 21

12%

Question 22

Silting

Answer 22

Grains of silt/sand build up and accumulate which kills fish

Question 23

Salinisation

Answer 23

Contamination of soil by sea water caused by flooding - kill crops

Question 24

Storm tide

Answer 24

The water level rise during a storm due to the combination of storm surge and astronomical tide

Question 25

Primary SEEP impacts

Answer 25

Enviromental:
* Beaches eroded
* Sand displaced
* Coastal habitats destroyed
Economic:
* Businesses destroyed
* Agricultural land damaged
Social:
* Drowing
* Debris - kills
* Buildings - destroyed
Political:
* Govt buildings destroyed

Question 26

Seondary SEEP impacts

Answer 26

Enviromental:
* Salinisation
* Animals displaced
* Water sources changing courses
Economic:
* Rebuilding and insurance payoit
* Incomes lost
* Economic decline
Social:
* Homelessness
* Polluted water supplies
* Diseases
* Food shortages and damage
Political:
* Issues payback of international aid
* Preesure laod more about global warming due to increased storm events

Question 27

The saffir- simspon scale

Answer 27

• Developed in 1971 as a means of enabbling storms of different magnitudes to be compared
• It is an absolute scale based on sustained windspeeds, air pressure and storm surge height
• Has 5 catergories - starting at 1 with wind speeds of 74-95mph
• Used mainly in North Alantic (measuring hurricane strength)

Question 28

Limitations of saffir simpson scale

Answer 28

• Doesnt measure the impact
• Doesnt measure rainfall intensity or area affected by the stomr
• low category cyclone that hits a densly populated urabn area - more damaging thna high category in remote regions

Question 29

Category 5

Answer 29

• Wind speed = 250km +
• Low pressure <920mb
• Storm surge >5.5m
• Potential damage - complete roof failture of many buildings, major damage to lower floors of all structures <3m evacuation of all buildings within 24km of coast

Question 30

Factors affecting the impacts of tropical storms?

Answer 30

• Population density
• Perspective of the storm ie fatalistic approach
• Level of preparedness
• Natural barriers ie mangroves
• topography of the land - coastal flat funnelling effect
• Economic diversity reliant on tourism
• Level of development ie odisha v new yeork
• Resources the country has avaliable
• The social saftey net benefits /security then reduces vulnerability
• Building density, infrastucture, stiltsm retrofitting
• Female name of storm - societial belief
• Time space the storm has been forming over

Question 31

Frequency and magnitude of storms

Answer 31

• The overall number of hurricanes has remained roughly the same, however there is evidence that they are intensifying more quickly, greater number of severe storms (4-5)
• The last two decades - several years with a high number of tropical storms - pattern is eratic
• Some logic - warming atmosphere - increased intensity of storm is countered by increased wind shear which acts as a negative feedback loop nuliffying storms intensity
• Proportion of storms that rapidly stregthen into powerful hurriacanes has tripeld in past 30 years
• Cost will increase - 2017 harvey,maria, irma cost combined 265bn
• US experienced a hurricane drough prior to 2017 bail to hurriance wima in 2008
• Climate breakdown - human activity - conditions are fiercer and more destructive hurricanes

Question 32

Is it possible to preict storms?

Answer 32

Yes:
* We know the latitudes that tropical storms develop in (tropics)
* We know the time of year they are likley to happen (summer-autumn)
* We know the approximate numbers that occur each year
* Technology allows us to measure sea temperature, atmosphereoc conditions and track climatic phenomenm such as el nino and la nina e.g. noaa
* Satellite tracking can monitor path and give likley landfall location

No:
* Climate is everchanging and data from previous years does not gurantee what the future will look like
* Tracking storms is not an exact science each will develop its own charactertistics and paths may change

Question 33

Hurricane return period

Answer 33

• It is possible to try to forecast the liklehood of future tropical storms events by looking at past reports
• By ranking the stregth of tropical storms at a particulat location it is possible to work out a tropical storm return period
• T = recurrence interval, N= the number of years of observation m = rank
• T = N+1 / M
• However it is a probability based on historic records, which may not be accurate
• The calculation does not factor in that tropical storms ma y occur less/more frequentley as it just gives a range
• Climate change may be increasing the frequency and intensity of tropicla storms
• Return period is only an average

Question 34

Prepare

Answer 34

Increasing awareness and taking action to reduce the impact of a storm event

Question 35

Stratergies for preparedness

Answer 35

• Education and public awareness campaigns - posters, radios, tvs
• Evacuation routes e.g. highways opened one direction
• Structural improvements to buildings - boarding windows, strapping down buildings
• Storm warnings via phone, tv,radio
• Evacuation centres- families know where to fo
• Sattelite imagery to monitor track of storm
• Insurance - afford to rebuild the damage to housing
• Computer models based on historical data enable scientists to preidct tje likley course or track of an individual storm e.g. hurricanw atch in usa and caanda when winds are expected in 36 hours before hurricae warning in next 24 h or less
• Large economic costs associated with evacuation must be accurate as people may not follow advice
• In usa per km of coasts costs 1 million to evacuate
• Evacuation costs can vary better in hics

Question 36

Cyclone mocha

Question 37

A hurricane return period

Answer 37

The frequenecy at which a certain intensity of hurricane can be expected within a given distance of a given location

Question 38

The slosh model

Answer 38

Used to eliminate storm surge height
uses historical data
takes into account shoreline characteristics
uses physics equations and computers
prediction to within +/- 20% accuracy