• Cyclone Jawad has hit the east coast of India particularly the State of Odisha and Andhra Pradesh.
  • Although the cyclone weakened and didn’t cause much damage, it highlighted that India’s cyclone management approach was largely based on evacuation.
  • Thus, India’s cyclone management must incorporate Mitigation and Preparedness measures. Mitigation means measures taken prior to the impact of a disaster to minimize its effects.
Consider the following statements:

1.    Jet streams occur in the Northern Hemisphere only.

2.    Only some cyclones develop an eye.

3.    The temperature inside the eye of a cyclone is nearly 10 C lesser than that of the surroundings.

Which of the statements given above is/are correct?

[a) 1 only

[b) 2 and 3 only

[c) 2 only

[d) 1 and 3 only

CYCLONE: GEOGRAPHY (Source – https://www.pmfias.com and https://vikaspedia.in/social-welfare/disaster-management-1/natural-disasters/cyclones)

  • Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing about large-scale destruction due to violent winds (squalls), very heavy rainfall (torrential rainfall) and storm surge.
  • They are irregular wind movements involving closed circulation of air around a low-pressure center. This closed air circulation (whirling motion) is a result of rapid upward movement of hot air which is subjected to Coriolis force. The low pressure at the center is responsible for the wind speeds.


  • Large sea surface with temperature higher than 27° C,
  • Presence of the Coriolis force enough to create a cyclonic vortex,
  • Small variations in the vertical wind speed,
  • A pre-existing weak low-pressure area or low-level-cyclonic circulation,
  • Upper divergence above the sea level system


  • The tropical cyclones have a thermal origin, and they develop over tropical seas during late summers (August to mid-November).
  • At these locations, the strong local convectional currents acquire a whirling motion because of the Coriolis force.
  • After developing, these cyclones advance till they find a weak spot in the trade wind belt.


  • Under favorable conditions, multiple thunderstorms originate over the oceans. These thunderstorms merge and create an intense low pressure system (wind is warm and lighter).


  • In the thunderstorm, air is uplifted as it is warm and light. At certain height, due to lapse rate and adiabatic lapse rate, the temperature of air falls and moisture in the air undergoes condensation.
  • Condensation releases latent heat of condensation making the air more warmer. It becomes much lighter and is further uplifted.
  • The space is filled by fresh moisture laden air. Condensation occurs in this air and the cycle is repeated as long as the moisture is supplied.
  • Due to excess moisture over oceans, the thunderstorm intensifies and sucks in air at much faster rate. The air from surroundings rushes in and undergoes deflection due to Coriolis force creating a cyclonic vortex (spiraling air column. Similar to tornado).
  • All the wind that is carried upwards loses its moisture and becomes cold and dense. It descends to the surface through the cylindrical eye region and at the edges of the cyclone.
  • Continuous supply of moisture from the sea is the major driving force behind every cyclone. On reaching the land the moisture supply is cut off and the storm dissipates.
  • If ocean can supply more moisture, the storm will reach a mature stage.


  • At this stage, the spiraling winds create multiple convective cells with successive calm and violent regions.
  • The regions with cumulonimbus cloud (rising limbs of convective cell) formation are called rain bands below which intense rainfall occurs.
  • The ascending air will lose moisture at some point and descends (subsides) back to surface through the calm regions (descending limbs of convection cell – subsiding air) that exist between two rain bands.
  • Cloud formation is dense at the center. The cloud size decreases from center to periphery.
  • Rain bands are mostly made up of cumulonimbus clouds. The ones at the periphery are made up of nimbostratus and cumulus clouds.
  • The dense overcast at the upper levels of troposphere is due to cirrus clouds which are mostly made up of hexagonal ice crystals.



  • The “eye” is a roughly circular area of comparatively light winds and fair weather found at the center of a severe tropical cyclone.
  • There is little or no precipitation and sometimes blue sky or stars can be seen.
  • The eye is the region of lowest surface pressure and warmest temperatures aloft (in the upper levels) – the eye temperature may be 10°C warmer or more at an altitude of 12 km than the surrounding environment, but only 0-2°C warmer at the surface in the tropical cyclone.
  • Eyes range in size from 8 km to over 200 km across, but most are approximately 30-60 km in diameter.


  • The eye is surrounded by the “eye wall”, the roughly circular ring of deep convection, which is the area of highest surface winds in the tropical cyclone. Eye Wall region also sees the maximum sustained winds i.e. fastest winds in a cyclone occur along the eye wall region.
  • The eye is composed of air that is slowly sinking and the eye wall has a net upward flow as a result of many moderate – occasionally strong – updrafts and downdrafts [Explained in ‘Thunderstorms’].
  • The eye’s warm temperatures are due to compressional warming (adiabatic) of the subsiding air.
  • Most soundings taken within the eye show a low-level layer, which is relatively moist, with an inversion above – suggesting that the sinking in the eye typically does not reach the ocean surface, but instead only gets to around 1-3 km of the surface.


  • Another feature of tropical cyclones that probably plays a role in forming and maintaining the eye is the eye wall convection.
  • Convection in tropical cyclones is organized into long, narrow rain bands which are oriented in the same direction as the horizontal wind.
  • Because these bands seem to spiral into the center of a tropical cyclone, they are called “spiral bands”.
  • Along these bands, low-level convergence is a maximum, and therefore, upper-level divergence is most pronounced above.
  • A direct circulation develops in which warm, moist air converges at the surface, ascends through these bands, diverges aloft, and descends on both sides of the bands.


  • Hazard Mapping: Hazard mapping for cyclones represents the results of cyclone hazard assessment on a map, showing the frequency/probability of occurrences of various intensities or durations.
  • Land Use Planning: Policies should be in place to regulate land use and enforcement of building codes.
    • Vulnerable areas should be kept for parks, grazing grounds or flood diversion instead of human settlements.
  • Engineered Structures: Some examples of general good construction practice include:
    • Constructing buildings on stilts or on earthen mounds.
    • Buildings should be wind and water resistant.
    • Buildings storing food supplies should be protected against the winds and water.
  • Cyclone Shelters: Cyclone Shelters are necessary for areas vulnerable to recurrent cyclones.
    • The construction of cyclone shelters requires substantial funding, therefore, generally linked to support from government or external donors.
    • For construction of cyclone shelters, the most appropriate sites should be selected, using the Geographical Information System.
  • Flood Management: Flooding will result from a cyclonic storm. Storm surges will flood the coastal areas. Heavy rains will bring in flash floods.
    • Embankments along the rivers, sea walls along the coasts may keep water away from the flood plains.
    • Water flow can be regulated through construction of reservoirs, check dams and alternate drainage channels/routes.
  • Mangrove Plantation: Mangroves protect the coastal area from storm surge and wind accompanied with cyclones.
    • Communities should participate in the mangrove plantation which could be organized by the local authorities, NGOs or the community itself.
    • Mangroves also help in erosion-control and coastal conservation.
  • Public Awareness Generation: Public awareness through education is the key to saving many lives. It has been proved that most of the damage to lives and livelihoods are due to lack of public education and awareness.
  • End to End Warning System: There is a need for an end-to-end early warning which will enable people at all levels to respond quickly and effectively.
  • The community should be well aware of the warning system, the warning signals and the source where they can get the early warning of cyclones.
  • Community Participation: Since the local people are the person’s best aware of the strengths and weaknesses of their area, location, culture and customs, some mitigation measures should be developed by the community themselves.
    • These community mitigation activities can be achieved with the support from government and other civil society organizations.


  • National Cyclone Risk Mitigation Project:
    • India initiated this project to undertake structural and non-structural measures to mitigate the cyclone’s effects.
    • The aim of the project is to protect the vulnerable local communities from the impact of cyclones and other hydro-meteorological calamities.
    • After the formation of National Disaster Management Authority (NDMA), the management of the Project was transferred to NDMA in September, 2006.
  • Integrated Coastal Zone Management (ICZM) Project:
    • The Ministry of Environment, Forest and Climate Change (MoEFCC) has unveiled the draft Environmental and Social Management Framework (ESMF) for Integrated coastal management.
    • The draft plan will dictate how prospective infrastructure projects would be assessed for clearance by laying out guidelines for coastal States.
  • Coastal Regulation Zones (CRZ):
    • The coastal areas of seas, bays, creeks, rivers, and backwaters which get influenced by tides up to 500 m from the high tide line (HTL) and the land between the low tide line (LTL) and the high tide line have been declared as coastal regulation zone (CRZ) in 1991.
    • The coastal regulation zones have been declared by the Ministry of Environment, Forest and Climate change under the Environment Protection Act 1986.
  • Color Coding of Cyclones:
    • It is a weather warning that is issued by the India Meteorological Department (IMD) to alert people ahead of natural hazards.
    • The four colors used by IMD are Green, Yellow, Orange, and Red.

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