The Caribbean region and the South Eastern United States of America are regularly subjected to the impact of tropical hurricanes;
(A)Briefly outline characteristics of such hurricanes.
The hurricanes that occur over the Caribbean region and the United States of America usually eventuate between August and October. For these hurricanes to occur the surrounding ocean temperatures must be minimal, also there must be a prolonged spell of equable temperature, pressure and humidity in the lower troposphere in conjunction with anti-cyclonic conditions in the upper troposphere. These conditions cause intense low pressure and strong winds at the earth’s surface. For their to be enough energy for the hurricane to move, it is essential that there is a considerable source of heat. This is necessary to maintain a consistent supply of rising air in the form of currents. There needs to be a large supply of moisture, as it is necessary for condensation to take place in order to release latent heat and it is the latent heat that initiates the development of the storm and consequently produces heavy rainfall.
When the hurricane reaches its maturity an eye develops in the centre, in the eye there is a relative area of subsiding pressure. Which is what causes clear skies, anomalous high temperatures and light winds. Eventually the eye disappears as a result of the descending air increasing instability, which in turn warms and increases the storms intensity. Around the eye there are towering Cumulo-nimbus clouds. The hurricanes decline as soon as the source of heat is lost/or removed. Although it can take between 9 and 15 days for this to happen. Winds immediately around a hurricane’s ‘eye’, which is usually about 32km (20 miles) across, reach more than 300 km/h (190 mph). But in the eye itself seen in the centre of the spiral-the weather is clear and calm.
(B)Identify the various types of damage caused by the passage of these hurricanes
Winds 118-152 Km/hour (64-82 Knots). Damage primarily to shrubbery, trees, poorly constructed signs, and unanchored mobile homes. No significant damage to other structures.
Storm surge 1-1.5m above tide. Low lying coastal roads inundated, minor pier damage, some small craft in exposed anchorages torn from moorings.
Winds 154-176 Km/hour (83-95 Knots). Considerable damage to shrubbery and tree foliage; some trees blown down.
Extensive damage to poorly constructed signs. Major damage to exposed mobile home. Some damage to exposed mobile homes. Some damage to roofing materials of buildings; some window and door damage. No major damage to buildings.
Storm surge 2-2.5m above normal tide. Coastal roads and low-lying escape routes made impassable by rising water 2-4 hours before arrival of hurricane centre. Considerable damage to piers. Marinas flooded. Small craft in unprotected anchorages torn from moorings. Evactuation of some shoreline residences and low-lying island areas required.
Winds 178-209 Km/hour (96-113 Knots). Foliage torn from trees; large trees blown down. Practically all poorly constructed signs blown down. Some damage to roofing materials of buildings; some window and door damage. Some structural damage to small buildings. Mobile homes destroyed.
Storm surge 2.5-3.5m above normal tide. Serious flooding at coast and many small structures near coast destroyed; large structures near coast damaged by battering waves and floating debris. Low-lying escape routes made impassable by rising water 3-5 hours before hurricane centre arrives. Flat terrain 1.5m or less above sea level flooded inland 13km or more. Evacuation of low-lying residences within several blocks of shoreline possibly required.
Winds 211-250 Km/hour (114-135 Knots). Shrubs and trees blown down; all signs blown down. Extensive damage to roofing materials, windows and doors. Complete failure of roofs on many smaller residences. Complete destruction of mobile homes. Storm surge 4-.5.5m above normal tide. Flat terrain 3m or less above sea level flooded inland as far 11km. Major damage to lower floors of structures near shore due to flooding and battering by waves and floating debris. Low lying escape routes made impassable by waters within 3-5 hours before hurricane centre arrives. Major erosion of beaches. Massive evacuation of all residences within 500m of shore possibly required, and of single-storey residences on low ground within 3 km of shore.
Winds greater than 250km/hour (135 knots). Shrubs and trees blown down; considerable damage to roofs of buildings; all sign down. Very severe and extensive damage to windows and doors with extensive shattering of glass components. Complete failure of roofs on many residences and industrial buildings. Some complete building failures. Small buildings overturned or blown away. Complete destruction of mobile homes.
Storm surge greater than 5.5m above normal tide. Major damage to lower floors of all structures less than 4.5m above sea level within 500m of shore. Low lying escape routes made impassable by rising water 3-5 hours before hurricane centre arrives. Massive evacuation of residential areas on low ground within 8-16km of shore possibly required.
(C)Suggest ways in which the destructive effects of hurricanes might be minimilised.
Higher standard of building, more modern durable materials as opposed to older weaker types. Better informed governments, educate governments on methods of prediction, prevention, and techniques on how to distribute aid to affected areas. Make available radar equipment and set-up/ develop metrological intelligence within a government/state etc. Eradicate threat of tidal surges. Concentrate expenditures on countries situated on the tropical cyclone belt. Plan rescue services for most efficient evacuation techniques etc.