Cyclone: rapid inward air circulation around a low-pressure area. The air circulates in an anticlockwise direction in the Northern hemisphere and clockwise in the Southern hemisphere.
The word Cyclone is derived from the Greek word Cyclones meaning the coils of a snake.
Tropical Cyclone: Intense low-pressure areas of the earth-atmosphere coupled system and are extreme weather events of the tropics.
- A tropical cyclone is a term used globally to cover tropical weather systems in which winds equal or exceed ‘gale force’ (minimum of 34 knots, i.e., 62 kmph).
Risk:
- Subcontinent with a long coastline of 8041 kilometres is exposed to nearly 10 percent of the world’s tropical cyclones.
- An analysis of the frequencies of cyclones during 1891-2000 shows that nearly 308 cyclones (out of which 103 were severe) affected the East Coast
States Prone:
Coastal States: The eastern coastal states like Odisha, Andhra Pradesh, West Bengal, and Tamil Nadu, as well as the western coastal states of Gujarat and Maharashtra, are prone to cyclones and tropical cyclones. The Bay of Bengal and the Arabian Sea are cyclone-prone regions.
Types of Tropical Cyclones:
- Hurricane (Atlantic and Northeast Pacific): These are powerful tropical cyclones with sustained winds of at least 74 mph (119 km/h). Example: Hurricane Katrina.
- Typhoon (Northwest Pacific): Similar to hurricanes, but the term “typhoon” is used in the Northwest Pacific region. Example: Typhoon Haiyan.
- Cyclone (Southwest Pacific and Indian Ocean): Cyclones are equivalent to hurricanes and typhoons but are referred to as cyclones in the Southwest Pacific and the Indian Ocean. Example: Cyclone Yasi.
- Tropical Storm: These are less intense than hurricanes, with sustained winds between 39 mph (63 km/h) and 73 mph (117 km/h). Example: Tropical Storm Harvey.
- Tropical Depression: The initial stage of a tropical cyclone, with maximum sustained winds below 39 mph (63 km/h). Example: Tropical Depression Barry.
- Super Typhoon (Western Pacific): A term used for exceptionally powerful typhoons with winds exceeding 150 mph (241 km/h). Example: Super Typhoon Meranti.
Criteria to Declare:
- Large sea surface with a temperature higher than 27° C;
- Presence of the Coriolis force;
- 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.
Causes:
- Warm Ocean Water: Cyclones are fueled by warm ocean waters, which provide heat and moisture, typically with sea surface temperatures of 26°C (79°F) or higher.
- Atmospheric Instability: Rising warm, moist air creates a low-pressure area that draws in more air, setting the cyclone in motion.
- Coriolis Effect: The rotation of the Earth causes the developing storm to spin, with the Coriolis effect.
Mitigation:
- Early Warning Systems: The India Meteorological Department (IMD) provides early warning forecasts and tracks the movement of cyclones, allowing for timely evacuations and preparedness.
- Evacuation Plans: Coastal states and regions prone to cyclones have evacuation plans, with designated shelters and routes.
- Cyclone Resistant Infrastructure: Building codes and construction standards in cyclone-prone areas
- Mangrove Conservation: Act as natural barriers against storm surges associated with cyclones.
NDMA Guidelines:
- If indoors:
- DROP to the ground, take cover by getting under a sturdy table or other piece of furniture, and HOLD ON until the shaking stops. If no table or desk is near you, cover your face and head with your arms and crouch in an inside corner of the building.
- Protect yourself by staying under the lintel of an inner door, in the corner of a room, under a table, or even under a bed.
- Stay away from glass, windows, outside doors and walls, and anything that could fall, (such as lighting fixtures or furniture).
- Stay in bed if you are there when the earthquake strikes. Hold on and protect your head with a pillow, unless you are under a heavy light fixture that could fall. In that case, move to the nearest safe place.
- If outdoors:
- Do not move from where you are. However, move away from buildings, trees, streetlights, and utility wires.
- If you are in open space, stay there until the shaking stops. The greatest danger exists directly outside buildings; at exits; and alongside exterior walls. Most earthquake-related casualties result from collapsing walls, flying glass, and falling objects.
Way Forward:
- Our response to cyclones and tropical cyclones must include advanced prediction systems, resilient infrastructure, community preparedness, and international cooperation.
- By investing in early warning systems and constructing cyclone-resistant buildings, we can save lives and reduce damage.
- Furthermore, addressing climate change is paramount to curbing the increasing intensity and frequency of these storms.
- In the face of these diverse and potent natural hazards, a holistic approach that combines science, technology, community engagement, and global collaboration is our best defence.
[Download PDF – Interview Dates]
