Cyclone Hazards

CYCLONE HAZARDS

Cyclones

Cyclones are huge revolving storms in the atmosphere with very strong winds circulating round a central area. 

The word cyclone is derived from the Greek, word cyclos meaning the coils of a snake.

In the northern hemisphere, a cyclone refers to an area of low atmospheric pressure surrounded by winds moving in a counter-clockwise direction.

The corresponding area of high atmospheric pressure with winds blowing in the clockwise direction is called an anti-cyclone.

 In the southern h hemisphere, the w wind directions are reversed. The intensity of the cyclones and the strength of winds depend on the amount of pressure drop in the centre and the rate of increase of pressure outwards

Types of Cyclones

The cyclones are classified as

 (i) Extra tropical cyclones (or) temperature cyclones

 (ii) Tropical cyclones. 

The world meterological organisation uses the term 'Tropical cyclone' to cover weather systems in which wind speed exceeds 63 km/hr.

Cyclones that develop in the regions between the tropics of capricorn and cancer are called tropical cyclones.

Extra tropical cyclones occur in temperate zones and high latitude regions. 

Categories of cyclone based on wind speed

The cyclones are classified into five different levels on the basis of wind speed and their capacity to cause damage.

Effects of cyclones

Some of the adverse effects of cyclones are (Fig. 5.9)

• Cyclones are associated with high pressure gradients. Consequently they result in strong winds which in turn generate storm surges.

• This causes sea water to inundate low-lying area of coastal regions drowning human beings and livestock.

• A storm surge is an abnormal rise of sea level near the coast. This causes sea water inundates low-lying areas of coastal region causing damage to human life and property.

• The cyclones erode beaches and embankments.

• They also destroy vegetation and reduces soil fertility. dgid bragg

• Very strong winds associated with cyclones may damage installations, dwellings, communication systems, trees, etc., and resulting in loss of life fe and property

• Heavy and prolonged rains due to cyclones lead to river floods and submergence of low-lying areas.

• Floods and coastal inundation due to storm surges pollute drinking water sources causing outbreak of epidemics.

Cyclone management 

Preventive measures of cyclone

Cyclone is a natural hazard and it is beyond human control. However, the damages caused by these cyclones can be minimized by using the following measures:

• Planting more trees on the coastal belt

• Construction of dams, storm shelter and wind breaks

• Construction of proper drainage and wide roads for quick evacuation.

Forecasting and Warning

• Forecasting a cyclonic event is the best measure of minimizing the losses due to a cyclone. Advanced systems of cyclone forecasting are now available in almost all the developed Nations of the world.

• Warning should be issued immediately to the concerned government agencies and to the general public.

Relief tasks

• Relief measures such as economic help and support by bloo to individuals, community and government and non-governmental organizations should be ensured.

• Awareness should be spread at all levels of the community to prepare everyone for emergencies.