Storm Hazards Flashcards
What are the characteristics of a tropical storm?
high winds
Storm surges
Coastal flooding
River flooding
Landslides
Outline the formation of tropical storms?
This means that the sea surface is warmer (above 27 degrees). This causes warm moist warm to rise (convection)
Secondly, the rising air cools and condenses which creates clouds
Condensation release latent heat, this further warms the air and it rises,cools and condenses and releases further latent heat-forms continuous upwards convection currents
As the storm develops, warm moist air is drawn into the low-pressure system over the arm ocean, providing more fuel for convergence
The rising air rotates due to the Coriolis force, forming convection currents into one tropical storm
Upper atmosphere air rotation spreads air outwards and away from the storm
(the 4 C’s)
Explain the distribution of tropical storms
Such storms occur between 5 and 20 degrees north and south of the equator
Highest sun concentration
Ocean warmed and hot air rises convection
Falls (10-20) north and south
Therefore hurricanes occur in these paces
Concentration near Central America, East Asia and the subcontinents
Secondary characteristics of distribution is due to the concentration of warm water at depths greater than 70m
Storms move from the equator north (if north of the equator) and south (if south of the equator)
Secondary characteristics of the distribution is due to the influence of the coriolis effect
How does the magnitude, lifespan and frequency of tropical storms vary?
tropical revolving storms are measured on the Saffir Simpson Scale, a 5 point scale based solely upon wind speed
The average lifespan of a tropical storm is around 7-14 days (although it is believed that they may last longer due to climate change)
Every year 80-100 storms develop, 80% become tropical revolving storms
Explain the primary effects (hazards) of a tropical storm?
the immediate effects of a tropical storm is strong winds (often exceed 150km/h)
Heavy rainfall (often exceeding 200-300mm)
Storm surges
Explain the secondary effects (hazards) of a tropical storm?
storm surges can cause structural damage to buildings, roads and bridges
Heavy rainfall can lead to severe flooding, landslides and mudslides
Storm surges often devastate low lying land such as river deltas and often cause the majority of deaths.
Explain the physical and human factors affecting the vulnerability of a population to a tropical storm?
the intensity
Warnings and community response
Preparedness made by a community
The geography of the coastal area
Distance from the sea
Speed of movement (length of time over an area)
What are the impacts of climate change on tropical storms?
increase in the intensity
Decrease in the number of tropical storms, but an intense increase in the frequency of the most intense ones
Slow moving tropical storms will become more common
(This is because of the increase in temperatures of the polar regions. Less temperature difference between the tropics and the polar regions)
Explain the management response PREVENTION for storm surges?
Like most other natural hazards, tropical cyclones can not be prevented. A number of techniques have been unsuccessful over the last 80 years ago
Seeding clouds with dry ice or silver iodide so that the storm loses more water over the ocean and therefore it has latent heat energy to be released over the land
Cooling the oceans with icebergs to reduce evaporation
Changing the radiation balance in the storm by blowing black soot into the storms
Exploding the storm apart with hydrogen bombs and blowing the storm away from land with giant fans
All these ideas fail to take into account the sheer size and power of tropical storms
Explain the management response PROTECTION, MITIGATION AND PREPARATION for storm surges?
weather bureaux (for example the National Hurricane Centre in Florida) are able to access data from weathering satellites that give a real-time view of the location, track, size and strength of a hurricane
Hurricane drills can be practised. In Florida, ‘project safeside’ is a hurricane awareness programme with precautionary drills for use in schools.
As cyclones tend to follow an erratic path, it is not always possible to give more than 12-18 hrs warning. This means that in less developed regions, where communication is poor, there is insufficient time for a proper evacuation
The Bangladesh ‘ Cyclone Preparedness program’ is an ; awareness campaign, early warning system, construction of shelters and education ( encourages local people to have emergency packs of food)
Emergency services need to be trained in hazard response and a coordination action plan is needed in advance
Insurance covers storm losses, this can reduce personal economic loss (not total economic loss). However it is very expensive and is not available in some high risk areas
Explain the management response ADAPTION for storm surges?
land use planning - used to identify the areas at greatest risk, eg, the risk of storm surges can limit certain types of development in certain areas
Building sea walls, breakwaters and flood barriers and putting houses on stilts
Retrofitting structures, so they are wind resistant and safer during an event.
However, (risk)
In poorer areas, the need for land usually outweighs planning consideration to avoid high risk areas so retrofitting buildings in high risk areas is important
