Meaning: A large-scale system of winds that spiral in toward a region of low atmospheric pressure. A cyclone’s rotational direction is opposite to that of an anticyclone. In the Northern hemisphere, a cyclone rotates counterclockwise; in the Southern hemisphere, clockwise.
- Tropical cyclones occur only near the equator, in warm ocean waters.
- Warm, wet air rises from near the surface of the ocean to produce a cyclone. As this air rises and travels away from the ocean’s surface, less air remains at the surface. As the heated air rises, it creates a zone of reduced air pressure beneath it.
- Air from higher-pressure regions in the vicinity rushes into the low-pressure zone. The incoming “cold” air then turns warm and wet, rising with it. The cycle goes on and on.
- The water in the air cools as the warmer, moist air rises and cools, forming clouds. The heat and water evaporating from the ocean surface feed the entire system of clouds and wind, which spins and expands.
- An eye forms in the center of the storm system as it rotates more quickly. With low air pressure, it is quite peaceful and clear in the eye. The eye is flooded with higher-pressure air from above.
When the spinning storm’s winds exceed 39 mph (63 kmph), the storm is classified as a “tropical storm“ When wind speeds surpass 74 miles per hour (119 kilometers per hour), the storm is classified as a “tropical cyclone“ or hurricane.
Mitigation Measures: Although cyclones are uncontrollable, their effects can be reduced by implementing effective and efficient mitigation policies and techniques. Below is a quick summary of the same.
- Early warning systems: Early warning systems installed along coasts may considerably aid forecasting methodologies, allowing for early evacuation of individuals in storm surge regions.
- Developing communication infrastructure: Communication is a critical component of cyclone disaster mitigation, but it is also one of the first services to be affected during storms. Amateur radio has grown in importance as a backup to traditional communications networks and as a tool for disaster relief.
- Permanent housing construction: Adequately built concrete houses that can endure severe winds and tidal waves are required.
- Creating community cyclone shelters: Having cyclone shelters in strategic places can help reduce human casualties. These shelters can be utilized as public utility facilities under normal circumstances.
- Creating shelterbelts: Tree-planted shelterbelts can function as excellent wind and tide barriers. They minimize soil erosion in addition to functioning as efficient windbreakers and protecting soil crops from harm.
- Education and training: Public awareness initiatives that educate the public on how to respond to cyclone warnings and prepare for them can help to reduce casualties.
Real Life Incidents:
- Cyclone Fani – 2019:Fani was a powerful cyclonic storm that struck the Indian state of Odisha earlier this month. It left a trail of devastation in its wake, killing more than 40 people and uprooting trees and communication systems, hurting the state’s economy and disrupting daily life. Fani quickly became an extremely severe cyclonic storm, reaching a peak intensity of a high-end very severe cyclonic storm on May 2. It was the equivalent of a strong Category 4 hurricane.
- Cyclone Ockhi–2017:During the 2017 North Indian Ocean cyclone season, Cyclone Ockhi was the most severe and one of the strongest tropical cyclones. Ockhi from the Arabian Sea hit mainland India, as well as Kerala, Tamil Nadu, and Gujarat’s coasts. Apart from leaving a vast path of destruction across the impacted regions, this hurricane claimed the lives of 245 individuals.
Meaning : A landslide is the movement of rock, earth, or debris down a sloped section of land. Landslides are caused by rain, earthquakes, volcanoes, or other factors that make the slope unstable. Geologists, scientists who study the physical formations of the Earth, sometimes describe landslides as one type of mass wasting. The term “landslide” encompasses five modes of slope movement: falls, topples, slides, spreads, and flows.
Cause: Almost every landslide is caused by a combination of factors. Slope movement occurs when the strength of the earth elements that make up the slope is exceeded by forces operating downslope (mostly gravity).
Variables that enhance the impacts of down-slope pressures, as well as factors that lead to low or reduced strength, are among the causes.
Rainfall, snowmelt, changes in water level, stream erosion, changes in groundwater, earthquakes, volcanic activity, disturbance by human activities, or any combination of these events can cause landslides in slopes already on the edge of moving. Underwater landslides can be caused by earthquake shaking and other reasons. Submarine landslides are the name for these types of landslides. Tsunamis are occasionally caused by submarine landslides, which inflict devastation to coastal regions.
- By limiting the exposure of people and infrastructure to landslides and physically managing the landslides, considerable reductions in the risks caused by landslides can be accomplished.
- Developmental initiatives that entail changing the terrain, exploiting natural resources, or altering the balancing load on the earth should be prohibited.
- Drainage, erosion control measures such as bamboo check dams, terracing, jute and coir netting, and rockfall control measures such as grass plantation, vegetated dry masonry wall, retaining wall, and most importantly, preventing deforestation and improving afforestation are some critical measures that could be taken to prevent further landslides.
There is no way to completely avoid disasters. Natural disasters are unavoidable. Early warning systems, meticulous preparation, and readiness on the side of the vulnerable population, on the other hand, might assist to reduce the number of people killed or injured as a result of these disasters.
Real-Life Incidents: In India, there have been a number of catastrophic and tragic landslides in recent years. Here is a list of some of the deadliest landslides you should be aware of:
- Guwahati landslide, Assam: Due to severe rainfall, the landslide occurred on September 18, 1948. Over 500 people were killed in the landslide, which also buried an entire town, according to sources.
- Darjeeling landslide, West Bengal: Around October 4, 1968, a landslide occurred. Floods prompted the landslide, which split the 60-kilometer roadway in half. Thousands of people were killed in the disaster, according to reports.
- Malpa landslide, Uttarakhand: Between August 11 and August 17, 1998, a series of landslides occurred in the village of Malpa, killing approximately 380 people when the whole community was washed away in the landslide. The landslide is one of India’s worst landslides.