Mighty Ockhi: creates havoc in the country

Context:

• Cyclones are a common natural phenomenon in the Indian coast particularly in the east.
• But cyclone Ockhi is the latest powerful cyclone and is unlike the other recent ones.

What is a cyclone?

• Cyclonerefers to any spinning storm that rotates around a low-pressure center.
• The low-pressure center is also referred to as the ‘eye’ of the storm.
• The areas enveloping the center are called ‘arms’ of the storm.
• All the action happens in the ‘arms’ area where the storm is throwing out all of its rain and wind.
• Cyclones are categorised by the maximum wind speed they generate.

Categories of cyclones:

Cyclone Ockhi:

• Ockhi was described as a ‘very severe cyclonic storm’.
• It is the third strongest category according to the definitions used by the India Meteorological Department (IMD).

What is the significance of cyclone Ockhi?

• The significance of cyclone Ockhi lies in the area in which it developed.
• Mostly, cyclones are known to originate in both the Bay of Bengal and the Arabian Sea sides of the northern Indian Ocean.
• But Ockhi originated near the south-western coast of Sri Lanka, and travelled very near the southern-most tip of the Indian mainland, along the coasts of Tamil Nadu and Kerala, towards the Lakshadweep islands, where it was at its most powerful.
• It weakened considerably after that and continued further, taking a north-easterly turn towards the Maharashtra and Gujarat coastlines, it is to be noted that cyclones in this area are not a common phenomenon.
• The death toll in rain-related incidents in Kerala climbed to 19, with six more bodies being recovered.
• 690 fishermen have been rescued in combined operations carried out by the Navy, Coast Guard and Air Force.

Why does the Bay of Bengal have more cyclones than the Arabian Sea?

• According to Meteorologists, the relatively colder waters of the Arabian Sea are not favorable to the formation and intensification of cyclones.
• Additionally, the eastern coast of India receives cyclones that form not just in the Bay of Bengal, mostly around the Andaman Sea near the Andaman and Nicobar Islands, but also those travelling from the Pacific Ocean, where the frequency of ‘typhoons’, as these are called there, is quite high.
• Most of these cyclones weaken considerably after encountering a big landmass.
• Therefore, these do not travel to the Arabian Sea side.
• The western coast of India thus witnesses only those cyclones that originate locally or the ones, like Ockhi, that travel from the Indian Ocean near Sri Lanka.

How cyclones are predicted?

• How early the forecast is depends on how far the meteorologists are from the place where the cyclone is emerging.
• Meteorologists around the world use modern technology such as satellites, weather radars and computers etc to track tropical cyclones as they develop.
• Meteorologists also use state-of-art technologies and develop modern techniques such as numerical weather prediction models to predict how a tropical cyclone evolves, including its movement and change of intensity, when and where one will hit land and at what speed.
• Official warnings are then issued by the National Meteorological Services of the countries concerned.

Role of World Meteorological Organization (WMO) in cyclone prediction:

• The World Meteorological Organizationframework allows the timely and widespread dissemination of information about tropical cyclones.
• As a result of international cooperation and coordination, tropical cyclones are increasingly being monitored from their early stages of formation.
• The activities are coordinated at the global and regional levels by WMO through its World Weather Watch and Tropical Cyclone Programmes.

What are the destructions caused by Cyclones?

• There are three elements associated with cyclones which cause destruction during its occurrence. These are:

Strong Winds/Squall:

• Cyclones are known to cause severe damage to infrastructure through high speed winds.
• Very strong winds which accompany a cyclonic storm damages installations, dwellings, communications systems, trees etc., resulting in loss of life and property.

Torrential rains and inland flooding:

• Torrential rainfall associated with cyclones ushers in unabated rain which gives rise to unprecedented floods.
• Heavy rainfall from a cyclone is usually spread over wide area and cause large scale soil erosion and weakening of embankments.

Storm Surge:

• A storm surge can be defined as an abnormal rise of sea level near the coast caused by a severe tropical cyclone.
• As a result of which sea water inundates low lying areas of coastal regions drowning human beings and life stock, causes eroding beaches and embankments, destroys vegetation and leads to reduction of soil fertility.

What are the measures to be taken?

• There are many structural and non-structural measures for effective disaster management of cyclones.

Structural measures:

• The structural measures include construction of cyclone shelters, construction of cyclone resistant buildings, road links, culverts, bridges, canals, drains, saline embankments, surface water tanks, communication and power transmission networks etc.

Non-structural measures:

• Non-structural measures include like early warning dissemination systems, management of coastal zones, awareness generation and disaster risk management and capacity building of all the stakeholders involved.