Cyclone: The Natural Disaster | Formation of cyclone

Introduction:

Cyclone a natural disaster in the ocean is very dangerous. All coastal people suffer a lot when nature comes in its own way. We still remember It was 18 October 1999 when Orissa was hit by a cyclone. Which has a wind speed of 200km/h. 45,000 houses were smashed and 7,00,000 people became homeless. And again the same area was hit by another cyclone on  29 October with much greater speed. This happens every single year that the world suffers from a severe cyclone. Which also causes great destruction to life and property. Can’t handle it wholly so many organizations take partial precautions and Predictions. We will be going to look after all the formations, Predictions, Casualties, Classifications, etc. Let’s start the journey here we begin.

What is a cyclone:

Cyclone i.e. the spinning storm, huge revolving storms caused by winds blowing around a central area where low pressure (or simply pressure area) with winds spiraling inwards. These winds blow counterclockwise in the Northern hemisphere and clockwise in the Southern hemisphere.

Classification of the cyclone:

There are two types of cyclones:

  • Tropical cyclone
  • Wave cyclone

Tropical cyclones:

As the name suggests, these types of cyclones are generated near the Equator. A tropical cyclone is a large-scale low-pressure system that is not associated with any fronts. It originating over tropical or subtropical waters. Tropical cyclobe has originated showers and thunderstorms, and a closed surface wind circulation around a well-defined center.

Since tropical cyclones vary in weather conditions, size, and characteristics. So they are divided into two principal types and 4 subtypes based on intensity.

Weak cyclone Strong cyclone
Tropical disturbancesHurricanes
Tropical depressionsTornadoes
disastrous cyclone

Tropical disturbances:

Tropical disturbances are migratory wave cyclones also called easterly winds (due to the association of easterly trade winds). Since it is the weakest tropical cyclone, therefore it sustained winds of at least 61kph. But it influences weather conditions of both tropical and subtropical areas and associated with cumulus clouds (yield moderate to heavy thunderstorms).

Tropical depression:

Tropical depressions are centers of low pressure surrounded by more than one isobars. Originate over the Bay of Bengal, the Arabian Sea, and the Indian ocean. So they move with the velocity of 40-50 km per hour and are highly variable. Sometimes even remain stationary at a place for several days. If it is strong it can even cause a flood. These types of cyclones generally influenced the weather conditions of India and North Australia.

Hurricanes and typhoons:

Hurricanes are the most disastrous and most violent hazards of all atmospheric disturbances. That tropical cyclone surrounded by more than one isobar. It is called Hurricanes in the USA and typhoons in China. Also called ‘willy willy’ in Australia. They move at a speed of 120km/hr. Sometimes one can be confused between hurricanes and temperate cyclones as they look similar. But they are different in origin, scale, impacts, and potential of management.

Tornadoes:

Tornadoes are short and small but are the most violent storms. It is also known as ‘twisters’. As the air in a thunderstorm rises, the surrounding air races in and fills the gap, thus forming a funnel. Tornadoes are also rapidly rotating winds that blow around a small area of intense low pressure. Their development depends on instability in the atmosphere, convergence, and strong updrafts in the air.

Wave cyclone:

Wave cyclones (also called temperate cyclones or simply depressions ) are atmospheric disturbances having low pressure in the center and increasing pressure outward. So these are produced in the middle latitudes 35°-65° characterized by converging and rising air. Because of varying shapes such as circular, elliptical, or wedge they are variously called ‘low’, ‘depression’, or ‘troughs’.These are produced due to convergence of two contrasting air masses from both the hemisphere like warm, moist and light air masses( westerly winds )converge with cold and dense polar air masses and hence as result, temperate cyclone formed.

Formation of the cyclone:

how cyclone is formed

Cyclones,i.e circulatory winds, are centers of low pressure surrounded by isobars having increasing pressure outward and closed air circulation from outside towards the central low pressure in such a way that air blows inward anticlockwise in the northern hemisphere and clockwise in the southern hemisphere. The formation of the cyclone is also quite a long process. When the atmospheric pressure is low above the water body warm air rises to fill the gap and the cold air settles down (containing moisture ). The warm air as it reaches the place becomes warmer and rises rapidly thus creating more gaps. So the surrounding air rushes to fill the place. This fills air travel with the greatest speed. From the longest distance, it reaches the area and starts circulating and creating a spiral from huge cyclones. And these spiral structures become larger penetrating clouds and create a thunderstorm.

How the Cyclone is Named:

Regional Specialized Meteorological Centers (RSMCs) and Tropical Cyclone Warning Centers (TCWCs) give names to the cyclones. Indian Meteorological Department(IMD) is also one of the RSMCs. Since 2002, the name of the cyclone was assigned by The World Meteorological Organization (WMO) along with the United Nations Economic and Social Commission for the Asia Pacific (ESCAP). IMD also names the cyclones arising in the Indian Ocean, Arabian Sea, and the Bay of Bengal. It also issued advisories and warnings to 12 other nations situated nearby at the time of the cyclone. So the naming of cyclones helps us in the identification. And also helps in spreading the message easily. And avoids the chances of confusion.

History of the cyclone:

The Eastern coast of India is near the sea so it has faced many disastrous cyclones in its history. One of them is the ‘great Orissa cyclone of 1999’. Which caused many casualties and killed around 9000 to 10000 people. This cyclone also has a wind speed of 155 mph and a storm surge of 26 feet. So this storm is classified as a ‘super cyclonic storm’.

In short most of the tremendous or deadliest storms of world history have occurred in the way of Bengal. But the worst and deadliest of all was ‘the great Bhola’ cyclone of 12-13 NOV., 1980. This 40-foot storm overwhelmed the Brahmaputra and Ganga river in Bangladesh. And causes overall deaths around 300,000 – 500,000.

YEARNAMEAREA OF OCCURRENCECASUALITIES
1970Great Bhola cycloneBay of Bengal, Bangladesh300,000-500,000
1737Hooghly river cycloneBay of Bengal, Bangladesh300,000
1881Haiphong TyphoonWest Pacific, Vietnam300,000
1839Coringa Bay of Bengal, Bangladesh300,000
1584Backerganj CycloneBay of Bengal, Bangladesh200,000
1876Great Backerganj CycloneBay of Bengal, Bangladesh200,000
1897ChittagongBay of Bengal, Bangladesh1,75,000
1975Super Typhoon NinaWest Pacific, China1,71,000
1991Cyclone 02BBay of Bengal, Bangladesh1,38,866
2008Cyclone NargisBay of Bengal, Myanmar1,38,366
top 10 deadliest cyclone in world

Warning System of the cyclone:

Indian Meteorological Department (IMD) provides the cyclone warning service in India based on quite old mechanisms. So IMD provides cyclone warning through Cyclone Warning centers ( CWCs) and Area Cyclone Warning centers (ACWCs). They are located at various places in India. IMD also has its setup based on satellite mechanisms to predict cyclonic activities and to issue warnings.

 The IMD issues cyclone warnings in four stages for the Indian coast. They are as follows:-

Stage 1.

Pre-Cyclone watch (yellow)– It contains the chances and likelihood of occurrence of cyclonic disturbance. And also the region which is likely to experience adverse weather. It Issued 72 hours ago.

Stage 2.

Cyclone alert ( orange)– It was issued 48 hours ago before the beginning of adverse weather over the region.

Stage 3.

Cyclone warning (red)– The landfall location, which will be affected by the cyclone, is discussed at this stage. It was issued 24 hours before the cyclone. It also indicated the latest position of the cyclone.

Stage 4.

Post-Landfall outlook– The path or track of the cyclone is discussed in this stage. It also deals with the discussion related to the possible damage or impact of the cyclone. It is actually issued 12 hours ago. District collectors of the areas were also informed in this stage to take suitable measurements.

Damage by the cyclone:-

Part 1:-

IntensityDamage expectedAction Suggested
Depression <31 kmph (<17 knots)As a result, it causes minor damage to loose and unsecured structuresTherefore fishermen advised not to venture into the open seas
Deep Depression
50 – 61 kmph
(28-33 knots)
As a result, it causes minor damage to loose and
unsecured structures
Therefore fishermen advised not to venture into the open seas.
Cyclonic Storm
62 – 87 kmph
(34-47 knots)
Damage to thatched huts.
Also breaking of tree branches
causing minor damage to
power and communication lines
Total suspension of fishing operations
Severe Cyclonic Storm
88-117 kmph
(48-63 knots)
Extensive damage to thatched
roofs and huts. So it causes minor damage to power and communication lines due to uprooting of large avenue trees. Flooding of escape routes
Total suspension of fishing
operations. Coastal huntsmen dwellers are also moved to safer places. People in affected areas to remain indoors.
Storm Intensity, Expected Damage and Actions Suggested

Part 2:-

IntensityDamage expectedAction Suggested
Very Severe Cyclonic
Storm
118-166 kmph
(64-89 knots)
Extensive damage to kutcha
houses. Partial disruption of
power and communication
line. Also minor disruption of rail and road traffic. Potential threat
from flying debris. Flooding of
escape routes
Total suspension of fishing
operations. Mobilize evacuation from coastal areas. Judicious regulation of rail and road traffic. People in affected areas to remain indoors.
Extremely Severe
Cyclonic Storm
167-221 kmph
(90-119 knots)
Extensive damage to kutcha
houses. Some damage to old
buildings. Large-scale disruption of power and communication lines. Disruption of rail and road
traffic due to extensive flooding Potential threat from flying debris.
Total suspension of fishing
operations. Extensive evacuation
from coastal areas. Diversion or
suspension of rail and road traffic. People in affected areas to remain indoors.
Super Cyclone
222 kmph and more
(120 knots and more)
Extensive structural damage to
residential and industrial
buildings. Total disruption of
communication and power
supply. Extensive damage to bridges causing large-scale disruption of rail and road traffic. Large-scale flooding and inundation of sea water. Air full of flying debris
Total suspension of fishing
operations. Large-scale evacuation of coastal population. Total suspension of rail and road traffic in vulnerable
areas. People in affected areas to
remain indoors.
Storm Intensity, Expected Damage and Actions Suggested
The guidelines, warning and essential instruction related to Storm Intensity, Expected Damage, and Actions Suggested given by India Meteorological Department

Property destruction:

Natural disasters make everything around destroys and hazardous situations. All the walls at the coastal sides break, trees around the cast uproot. And small houses of fisherman get destroyed in this situation, etc. Nature has its own way of living and it can be predicted. Also, we can predict the reason for that natural calamity. But we can’t predict the damage (that is going to cause) exactly. The measures were taken by the government to make people aware of the conditions. They do it by press release, arrangement of the NDRF team around the coastal region. Fishermen are also told not to go in the ocean at that date, etc. But no one knows what is the aim of nature.

Conclusion:

Cyclones are one of the great hazardous natural disasters. It causes many casualties not only death but also the destruction of properties. So everyone should be aware of it and must have sufficient knowledge about it. In this article, we define the cyclone and its types and classifications. We also define hurricanes, typhoons, and tornadoes. This article also discussed the essential knowledge about the formation of cyclones. Some points of this article also discussed how the cyclones are named. And the history of the cyclones. The Indian Meteorological Department (IMD) is one of the six Regional Specialised Meteorological Centres (RSMCs). So IMD provides names, prediction, warning, expected damage and action suggested at the time of the occurrence of the cyclone. We try to include as much information about the cyclone as possible in the best and easiest language. We hope you enjoyed the article.

References

  1. The above table is by IMD, Ministry of earth science
  2. Measurement scale detail RSMC, pdf
  3. The warnings by RSMC for cyclones we included.

FAQ

What cyclone means

That spinning storm, huge revolving storms caused by winds blowing around a central area where low pressure or simply pressure area with winds spiraling inwards…

How cyclones are named

The name of the cyclone is given to Regional Specialized Meteorological Centers (RSMCs) and Tropical Cyclone Warning Centers (TCWCs). Indian Meteorological Department(IMD) is also one of the RSMCs. Since 2002, the name of the cyclone was assigned by The World Meteorological Organization (WMO) along with the United Nations Economic and Social Commission for the Asia Pacific (ESCAP).

Can cyclones be predicted

IMD has its setup based on satellite mechanisms to predict cyclonic activities and to issue warnings. Indian Meteorological Department (IMD) provides the warning service in India based on quite old mechanisms.

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