Tropical cyclone hazard

Storm surge - rapid rise in sea level - water piles up against coastline (higher than usual)

    -is produced during passage of tropical storm.

    - wind-driven waves pile up water onto coastline 

    -combined with ocean heaving upwards due to low air pressure

Coriolis force - makes storm rotate clockwise in southern hemisphere, N i- anti-clockwise

Eye - develops when:

-supply of latent heat & moisture to provide energy and frictional drag on ocean surface

  -10-15km diameter

 -calm clear skies, increase in temperature

-windspeed = 300km/hr

Tropical storm - intense low pressure weather systems, develops in tropics. 200-700km diameter

Conditions for tropical storm:

1. Sea temp 27 degrees, source of heat to maintain rising air currents

2. Ocean depth 70m - moisture provides latent heat; rising air causes moisture to be released (condensation)

3. 5 degreees north or south of equator - Corolis force can bring maximum rotation (force weak at equator)

4. Low level covergence of air in lower atmospheric circulation system - as winds have to come together near centre of low-pressure zone

5. Rapid outflow of air in upper atmosphere circulation - pushes warm air away (which has risen close to centre of storm)

Hurricane - Carribean Sea / Gulf of Mexico (11%)  ,  Western side of Central America (17%)

Cyclones - Arabian Sea / Bay of Bengal (8%)

Typhoons - SE Asia (1/3 of all storms per year)

(Australia - willy-willies)

Saffir-Simpson scale - magnitude of tropical revolving storm (5 point scale) based on:

-central pressure (920mb or below)

-wind speeds (250km/hr or greater)

-damage potential

Average lifespan of storm - 7-14 days. 80% of all storms turn into tropical revolving storms

Cumulonimbus - bulbous cloud from rising air currents

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Impacts of tropical revolving storm:

- intensity of storm 

-speed of movement

-distance from sea

-physical geography of coastal area

-preparations made by community

-community response

WIND

structural damage to buildings and infrastructure, debris risk to humans / property

HEAVY RAINFALL

can exceed to 200-300mm. Severe flooding, land / mud slides

STORMSURGES

low lying coastal areas, flooding agricultural land. Soil contaiminated with sea water.

Prediction:

-using geostationary satillites to monitor

-weather aircraft for constant surveillance

-predict path using computer models to evacuate predicted areas

^ BUT hurricanes have erratic path (gives little notice)

Prevention:

-can't be prevented

-research in cloud seeding - causes more precipitation - if releases more water, storm becomes weaker before reaching in land

Protection:

-evacuation - in USA National Guard ensures no looting

-educating community - how to strengthen homes, evacuation 

-cyclone drills in work places / school

-retrofitting structures to be more resilient to wind

-land use planning - introducing sea wall, flood barriers in areas of high risk

Preparedness:

-aid, communication, education             -richer people take insurance

-land use planning, good intrastructure

-eg. USA use Out Banks Mitigation Plan to save lives money and property by reducing vulnurabilty and encouraging speedy recovery