Cyclone in India

 Cyclone in India

image sources: https://commons.wikimedia.org/w/index.php?curid=1214111

When a system of winds rotates inwards at a high speed with an area of low pressure in the middle is known as a cyclone.

CYCLONES are atmospheric disturbances and are formed around a low-pressure area. It is distinguished by swift and often destructive air circulation.

It is classified into:

Tropical cyclones

Extratropical/Temperate cyclones

Tropical cyclones are of thermal origin. That is, it owes its origin to the warmness of ocean water. It occurs between the Tropic of Cancer and the Tropic of Capricorn. Whereas, the temperate cyclone is of frontal origin.

India with a long coastline of 7516.16 km is one of the worst affected regions, where it is exposed to around 10% of tropical cyclones in the world.

Tropical cyclone

It is an intense low-pressure center associated with the convergence of wind rotating inwards to the low-pressure point forming a closed cyclonic vortex. Coriolis force and the rapid inward circulation to the low-pressure area is the reason behind the formation of the cyclonic vortex.

The Center of the low-pressure area is called the EYE region where the atmosphere is calm. But the area around the eye region (eyewall) is associated with the violent movement of the wind.

It begins as a low-pressure area to a super cyclone depending on the speed of the wind. It consists of a cumulonimbus cloud with torrential rainfall.

Tropical cyclones are among the foremost destructive weather phenomena and are also known as typhoons or hurricanes.

• In the Atlantic Ocean and the eastern North Pacific Ocean, it is known as Hurricanes.
• In the western Pacific Ocean, it is known as Typhoons.
• In the South Pacific Ocean and the Indian Ocean, it is known as Tropical cyclones. 

Tropical cyclone wind field may be divided into three regions:

• Ring-shaped outer region and an inner radius of about 30 to 50 km. In this region, the speed of the wind increases uniformly toward the center.
• At the second region that is the eyewall, wind speed attains their maximum value which is typically 15 to 30 Km from the center of the storm.
• Further, the eyewall, in turn, surrounds the interior region known as the eye where the speed of the wind decreases rapidly and the air is often calm.

Tropical Cyclone formed

The tropical cyclone is formed when a transfer of water vapor and heat from the warm ocean to the overlying air occurred primarily by evaporation from the surface of the sea. As we know that warm, moist air rises, expands, and cools, quickly and becomes saturated, and released latent heat due to the condensation of water vapor. By this process, the column of air in the core of the developing disturbance is warmed and moistened.  The temperature difference is formed between the warm, rising air and the cooler environment that causes air to become buoyant and enhance its upward movement.

Temperate Cyclone (Extra-Tropical Cyclones)

• The Extra-Tropical Cyclones are storm systems emerging in the mid and high latitudes, away from the tropics.
• They are low-pressure systems with associated cold fronts, warm fronts, and occluded fronts.
• These cyclones are formed along the polar front.
• In the beginning, the front is stationary.
• Extra-tropical cyclones are also known as mid-latitude storms or baroclinic storms.
• In the Northern hemisphere, cold air blows from the north of the front, and warm air blows from the south.
• When the pressure descents along the front, the cold air move towards the south, and the warm air moves northwards setting in motion an anticlockwise cyclonic circulation.
• The cyclonic circulation results in a well-built extratropical cyclone, with a cold front and a warm front.

Tropical Cyclone	Temperate Cyclone
tropical cyclones, move from east to west.	These cyclones move from west to east
A tropical cyclone has an effect on a comparatively smaller area than a Temperate cyclone.	Temperate cyclones affect a much larger area
The velocity of wind in a tropical cyclone is much higher and it is more damaging.	The velocity of air is comparatively lower
Tropical Cyclone forms only on seas with temperatures more than 26-27degree C and dissipates on reaching the land.	Temperate cyclones can be formed on both land and sea
A tropical cyclone doesn’t last for more than 7 days	Temperate cyclones can last for a duration of 15 to 20 days

Favorable conditions for Cyclones

A low-pressure condition where I.T.C.Z forms 5 to 8degree away from the equator.

Sea surface temperature should be more than 27-degree Celsius.

An adequate amount of vapor supply through evaporation.

Differential heating of land and sea.

Strong anticyclonic divergence in the upper atmosphere.

Effects of cyclones

Strong winds/Squalls: Through high-speed winds, cyclones cause severe damage to the infrastructure. Installations, dwellings, communication systems,s, etc. get destroyed resulting in loss of life and property.

Torrential rains and inland flooding: Continuous rains cause floods resulting in loss of shelter. Also, heavy rains due to cyclones cause landslides, soil erosion and weaken the embankments.

Storm surge: An abnormal rise in sea level near the coast due to severe tropical cyclones results in the drowning of low-lying areas in the coastal region. It results in loss of lives, destruction of vegetation and the salt content in seawater reduces the soil fertility.

Indian Context

The majority of the cyclones affecting India originate from the Bay of Bengal striking the eastern coast. The ratio of occurrence of cyclones between the Bay of Bengal and the Arabian sea is approximately 4:1. This is because of less salinity, which is due to more inflow of freshwater and high sea surface temperature in the Bay of Bengal.

Cyclones in India occurs during the month of May, June, October, and November.

Cyclones like Nada, Varda, Hudhud, Phailin, etc. caused loss of property in the eastern part of India. Recently, a severe cyclonic storm Ockhi resulted in the loss of lives and damage to properties in Tamil Nadu and Kerala.

Current Situation of Disaster Preparedness and Management in India

India is highly vulnerable to natural disasters especially cyclones, earthquakes, floods, landslides, and drought. Natural disasters cause a loss of 2% of GDP every year in India. According to the Home ministry, 8% of the total area in India is prone to cyclones.

Indian Meteorological Department (IMD) is the nodal agency for early warning of cyclones and floods.

Natural Disaster Management Authority is mandated to deal with disaster management in India. It has prepared National Guidelines on Management of Cyclone.

National Cyclone Risk Mitigation Project (NCRMP) was launched by the Home Ministry to upgrade the forecasting, tracking, and warning about cyclones in states.

National Disaster Response Force (NDRF) has done a commendable performance in rescuing and managing relief work.

National Disaster Response Reserve (NDRR)- a fund of 250 crores operated by NDRF for maintaining inventory for an emergency situation.

In 2016, a blueprint of the National Disaster Management Plan was unveiled to tackle the disaster. It provides a framework to deal with prevention, mitigation, response, and recovery during a disaster. According to the plan, the Ministry of earth science will be responsible for disaster management of cyclones. By this plan, India joined the list of countries that follow the Sendai Framework for Disaster Risk Reduction 2015-2030.

Due to increased awareness and tracking of cyclones, the death toll has been reduced substantially. For example, Very severe cyclones Hudhud and Phailin claimed the lives of around 138 and 45 people respectively, which might have been more. It was reduced due to the early warning and relocation of the population from the cyclone-hit areas. Very severe cyclone Ockhi claimed many lives of people in Tamil Nadu and Kerala. This was due to the unprecedented change in the direction of the cyclone.

But the destruction of infrastructure due to cyclonic hits is not been reduced which leads to an increase in poverty due to the economic weakening of the affected population.

Problems in Disaster Preparedness and Management

• One-third of the population in India lives in the coastal area. Most of them are marginalized people who are ill-prepared and unable to cope up with a disaster.
• India considers post-disaster response as an important activity. Hence institutional systems, manuals, policies, programs are designed to address these concerns. Redefining this is not yet complete.
• There is a lack of proper coordination between the central and state government and their agencies.
• The warning of a cyclone is not properly communicated between the concerned agencies. In many cases, the warning is not taken seriously by the agencies which cause delayed effort for the prevention of a disaster. This was evident in the recent Ockhi cyclone disaster.
• Lack of awareness of people about the impact and magnitude of the disaster.
• Mining and other industries in the ecologically sensitive area, lack of compliance with zoning and building regulation codes is increasing the death toll.
• Indian laws follow the international norms which make it illegal for small fishing vessels to carry communication equipment that could help in saving lives during a disaster.