In recent news, the India Meteorological Department (IMD) has issued alerts as a deep depression over the Bay of Bengal is likely to intensify into a cyclonic storm. This serves as a reminder of the critical need to understand cyclones and prepare effectively to mitigate their devastating impacts. As cyclones have become increasingly frequent and intense, they pose significant challenges to vulnerable coastal regions, demanding collective action and awareness.
What Are Cyclones?
Cyclones are large-scale air masses that rotate around strong low-pressure systems. They are characterized by strong winds, heavy rainfall, and spiraling clouds, which can lead to widespread destruction, flooding, and loss of life. Cyclones are classified based on their geographic occurrence and intensity, with tropical cyclones often garnering more attention due to their ferocity.
How Are Cyclones Formed?
Cyclones are formed under the following conditions:
Warm Ocean Waters: Sea surface temperatures above 27°C provide the energy needed for cyclogenesis.
Low-Pressure Systems: A disturbance over warm waters triggers rising air, forming a low-pressure center.
Coriolis Effect: Earth's rotation causes the air to spiral, creating a cyclonic pattern.
High Humidity in the Troposphere: Moist air fuels the system, intensifying its strength.
Minimal Wind Shear: Stable vertical wind allows the cyclone to organize and grow.
Tropical vs. Temperate Cyclones
The following table highlights the differences between tropical and temperate cyclones:
Aspect
Tropical Cyclones
Temperate Cyclones
Formation Region
Over warm tropical oceans
Mid-latitude regions between 30° and 60° latitude
Energy Source
Latent heat from warm ocean waters
Temperature contrast between air masses
Seasonality
Typically during late summer to autumn
Can occur throughout the year
Wind Speed
High (over 119 km/h for hurricanes, cyclones, typhoons)
Moderate
Structure
Symmetrical with a clear eye at the center
Asymmetrical with fronts
Naming Method for Cyclones in the Indian Ocean
Cyclones in the Indian Ocean are named based on a rotational list developed by member countries of the World Meteorological Organization (WMO). For instance, recent cyclones such as Mocha and Mandous were named following this systematic approach. The naming helps in easy identification and public awareness.
Why Are Cyclones More Frequent in the Bay of Bengal?
The Bay of Bengal witnesses more cyclones than the Arabian Sea due to:
Warm Waters: The Bay of Bengal has higher sea surface temperatures, providing favorable conditions for cyclogenesis.
Geographical Layout: Its funnel shape amplifies the intensity and frequency of storms.
Calm Winds: Lower wind shear in the region supports cyclone formation.
Moisture Content: The bay receives runoff from major rivers, adding humidity to the atmosphere.
In contrast, the Arabian Sea has cooler waters and higher wind shear, which act as deterrents to cyclone formation.
Effect of La Niña and El Niño on Cyclones in the Indian Ocean
The phenomena of La Niña and El Niño, part of the El Niño-Southern Oscillation (ENSO) cycle, significantly influence cyclone activity in the Indian Ocean:
La Niña
Increased Cyclones in the Bay of Bengal: La Niña conditions typically cool the central and eastern Pacific Ocean, shifting the warm water pool toward the western Pacific and the Indian Ocean. This leads to increased sea surface temperatures in the Bay of Bengal, creating favorable conditions for cyclone formation.
Intensified Storms: The enhanced moisture and reduced vertical wind shear during La Niña result in stronger and more frequent cyclones.
El Niño
Reduced Cyclones in the Bay of Bengal: During El Niño, the warming of the central and eastern Pacific suppresses convection and cyclone activity over the Indian Ocean.
Shift to the Arabian Sea: The Arabian Sea, which is usually less cyclone-prone, may see increased activity due to elevated sea surface temperatures during El Niño years.
Example of ENSO Impact
La Niña: The 2020 cyclone season, influenced by La Niña, saw intense cyclones like Cyclone Amphan, which caused widespread destruction in eastern India and Bangladesh.
El Niño: In contrast, during the 2015 El Niño year, the Bay of Bengal witnessed suppressed cyclone activity, while the Arabian Sea saw an unusual increase, with events like Cyclone Chapala.
The ENSO cycle's influence highlights the interconnectedness of global climatic systems and their impact on regional weather patterns, emphasizing the need for dynamic forecasting and preparedness strategies.
Different Names for Cyclones Around the World
Cyclones are known by different names in various regions:
Hurricanes: Atlantic Ocean and Eastern Pacific
Typhoons: Western Pacific Ocean
Cyclones: Indian Ocean and South Pacific
Willy-Willies: Australia
Baguios: Philippines
These regional names emphasize their global nature and varying impacts.
Government’s Initiatives to Mitigate the Effects of Cyclones
The Indian government has undertaken several measures to reduce cyclone impacts:
Early Warning Systems: IMD's advanced forecasting techniques provide timely alerts.
National Cyclone Risk Mitigation Project (NCRMP): Strengthens disaster preparedness, coastal infrastructure, and community awareness.
Relief and Rehabilitation: Rapid deployment of disaster response forces (NDRF) and efficient relief measures post-cyclone.
Coastal Regulation Zones (CRZ): Policies aimed at sustainable development and reduced vulnerability in coastal areas.
Cyclone Shelters: Construction of safe havens in cyclone-prone regions.
Recent examples, such as the handling of Cyclone Yaas and Cyclone Tauktae, showcase India's growing resilience and preparedness.
Conclusion
Cyclones are a stark reminder of the power of nature and the vulnerability of human settlements. With advancements in forecasting and disaster management, the loss of life and property can be minimized. However, tackling cyclones requires continued investment in infrastructure, international collaboration, and awareness campaigns to ensure that at-risk populations are well-prepared. The current alerts over the Bay of Bengal underscore the importance of staying vigilant and adaptive in the face of climate-related challenges.
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