Here is a compilation of essays on ‘Cyclone’ for class 6, 7, 8, 9, 10, 11 and 12. Find paragraphs, long and short essays on ‘Cyclone’ especially written for school and college students.
Essay on Cyclones
- Essay on the Definition of Cyclone
- Essay on the Occurrence of Cyclone
- Essay on the History of Cyclones in India
- Essay on the Nature of Cyclone
- Essay on the Signs of Cyclone
- Essay on the Causes of Cyclone
- Essay on the Types of Cyclone
- Essay on the Vulnerability to Cyclones
- Essay on the Impact of Cyclone on the Coastal Ecosystem
Essay # 1. Definition of Cyclone:
Cyclones are also termed as atmospheric disturbances. They range in shape from circular, elliptical to ‘V’ shape. When the velocity of winds increases to such an extent that they attain gale force, the atmospheric disturbance or cyclone is called a cyclonic storm.
Cyclones are centres of low pressure surrounded by closed isobars having increasing pressure outward and closed air circulation from outside towards the central low pressure in such a way that air blows inward in anticlockwise in the northern hemisphere and clockwise in the southern hemisphere.
A tropical cyclone is a low-pressure system which develops in the tropics and is sufficiently intense to produce sustained gale force winds of at least 63km/h. If the sustained wind reaches hurricane force of at least 118km/h the system is defined as a severe tropical cyclone. In other parts of the world they are called hurricanes or typhoons.
Tropical cyclones can cause significant phenomena which can adversely, and sometimes favourably impact on communities and the environment. The most common features are destructive winds and heavy rainfall that can lead to flooding.
Storm surge, or coastal inundation by seawater, is a lesser known phenomenon but can be the most dangerous element of a cyclone. Though rare in Australia, tornadoes have been reported, during cyclone events.
Essay # 2. Occurrence of Cyclone:
In an average season, tropical cyclones are mostly experienced in northwest Australia between Exmouth and Broome in Western Australia and in northeast Queensland between Port Douglas and Maryborough.
In the Australian region, the official tropical cyclone season runs from 1 November to 30 April with most occurring between December and April. On an average, about 10 cyclones develop over Australian waters each year and around six of these cross the coast.
There is some correlation between cyclone frequency and the El-Nino Southern Oscillation status, with activity subdued in El-Nino events and enhanced during La-Nina events, especially in the Coral Sea.
Essay # 3. History of Cyclones in India:
Although cyclones affect the entire coast of India, the East Coast is more prone compared to the West Coast. An analysis of the frequencies of cyclones on the East and West coasts of India during 1891-2000 shows that nearly 308 cyclones (out of which 103 were severe) affected the East Coast. During the same period 48 tropical cyclones crossed the West Coast, of which 24 were severe cyclonic storms.
Out of the cyclones that develop in the Bay of Bengal, over 58 per cent approach and cross the east coast in October and November. Only 25 per cent of the cyclones that develop over the Arabian Sea approaches the west f coast. In the pre-monsoon season, corresponding figures are 25 per cent over the Arabian Sea and 30 per cent over the Bay of Bengal.
Essay # 4. Nature of Cyclone:
Though the frequency of Tropical Cyclones in the North Indian Ocean (NIO) is the least in the world (7% of the global total), their impact on the coasts bordering the North Bay of Bengal (North of 150 N latitude) in India as well as in the Bangladesh are extremely disastrous.
The problem can be fathomed from the fact that during the past two and a half centuries, 20 out of 23 major cyclone disasters (with human loss of life 10,000 or more and not considering the damage) in the world have occurred over the Indian Subcontinent (India and Bangladesh).
One of the major reasons for this is the serious storm tide problem in these coasts. A tropical cyclone of specific intensity when it strikes the east coast of India and Bangladesh, usually produces a higher storm surge compared to that when such a cyclone strikes elsewhere in the world.
This is because of the special nature of the coastline, the shallow coastal ocean topography and the characteristics of tide in the North Bay of Bengal region. Further, the high density of population, low awareness of the community about cyclones and their risks, inadequate response and preparedness add to the severity of the problem.
There are 13 Coastal States and UTs in the country, with about 84 coastal districts affected by tropical cyclones. Four States (Tamil Nadu, Andhra Pradesh, Odisha and West Bengal) and one UT (Puducherry) on the East Coast and one State (Gujarat) on the West Coast are the States that are more vulnerable to cyclone disasters.
Essay # 5. Signs of Cyclone:
i. Severe Wind:
In tropical cyclones, wind gusts in excess of 90 km/h can be expected around their centre, or eye, while in the most severe events, gusts can exceed 360 km/h. Although the strongest winds are near the eye, damaging winds can extend hundreds of kilometres from the centre.
The eye can have quite calm winds and cloud- free skies, but this lull is temporary and is followed by destructive winds from another direction. This is because, from above, the winds spiral around the eye in a clockwise direction (in the Southern Hemisphere). The effect of this on the ground is that winds on opposite sides of the eye blow in different directions.
Wind damage is mostly caused by the maximum gusts in the cyclone. For this reason, the well-known tropical cyclone severity categories used by the Bureau of Meteorology to communicate warnings are based on maximum gust strengths.
ii. Heavy Rainfall:
Because tropical cyclones formed over warm tropical oceans, they generally hold enormous amounts of moisture and can produce heavy rainfall over extensive areas. Rain can create severe impacts by causing floods and landslides through the direct damage of materials by contact, such as being driven by wind into the buildings. Direct damage is generally the result of wind damage to the walls, windows or roofs, which allows water to penetrate the buildings.
Rainfall can be associated with the tropical cyclone when it impacts on the coast or further inland as it weakens to become a tropical depression. Heavy rain from tropical cyclones or tropical depressions can often reach Australia’s more southerly latitudes where the rainfall is a major source of water for the country’s inland river and groundwater systems. Flooding can wreak havoc over vast areas, inundating land, isolating communities and destroying infrastructure.
iii. Storm Surge:
Potentially the most dangerous hazard associated with tropical cyclones which make landfall is storm surge. Storm surge has been responsible for more deaths than any other feature of tropical cyclones. Storm surge is a raised dome of water about 60 to 80 kilometres across and typically about two to five metres higher than the normal tide level.
It is caused by a combination of strong winds driving water onshore and the lower atmospheric pressure in a tropical cyclone. In the southern hemisphere the onshore winds occur to the left of the tropical cyclone’s path. In Australia, this is the east side on the north-west and north coasts and the south side on the east coast.
The largest surge usually extends between 30-60 kilometres from the crossing point of the tropical cyclone centre, or eye. Its influence also depends on the local topography of the seafloor and the angle at which the cyclone crosses the coast. If the surge occurs at the same time as a high astronomical tide the area inundated can be extensive, particularly along low-lying coastlines.
Essay # 6. Causes of Cyclones:
The main source of energy for tropical cyclones is the warm oceans in the tropical regions. To initiate a tropical cyclone the sea-surface temperature generally needs to be above 26.5°C. However, existing cyclones often persist as they move over cooler waters.
The development of a tropical cyclone also relies on favourable broad-scale wind regimes and can persist for several days with many following quite erratic paths. They lose their source of energy when they move over land or colder oceans causing them to dissipate.
Weakening may also occur if the cyclone moves into an unfavourable wind regime which disrupts the structure of the system. Sometimes a decaying tropical cyclone may interact with a weather system in higher latitudes to cause impacts far from the tropics.
Essay # 7. Types of Cyclones:
i. Extra Tropical Cyclones:
The systems developing in the mid and high latitude, beyond the tropics are called the middle latitude or extra tropical cyclones. The passage of front causes abrupt changes in the weather conditions over the area in the middle and high latitudes.
Extra tropical cyclones formed along the polar front. The cold front moves faster than the warm front ultimately overtaking the warm front. The warm air is completely lifted up and the front is occluded and the cyclone dissipates.
ii. Tropical 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 caused by violent winds, very heavy rainfall and storm surges. They are known as Cyclones in the Indian Ocean, Hurricanes in the Atlantic, Typhoons in the Western Pacific and South China Sea, and Willy-willies in the Western Australia.
Tropical cyclones originate and intensify over warm tropical oceans.
The conditions favourable for the formation and intensification of tropical storms are:
(i) Large sea surface with temperature higher than 27°C;
(ii) Presence of the Coriolis force;
(iii) Small variations in the vertical wind speed;
(iv) A pre-existing weak low-pressure area or low-level- cyclonic circulation;
(v) Upper divergence above the sea level system.
A mature tropical cyclone is characterized by the strong spirally circulating wind around the centre, called the eye. The diameter of the circulating system can vary between 150 and 250 km. From the eye wall rain bands may radiate and trains of cumulus and cumulonimbus clouds may drift into the outer region.
The diameter of the storm over the Bay of Bengal, Arabian Sea and Indian Ocean is between 600 and 1200 km. The system moves slowly about 300-500 km per day. The cyclone creates storm surges and they inundate the coastal low lands.
iii. Thunderstorms and Tornadoes:
They are of short duration, occurring over a small area but are violent. Thunderstorms are caused by intense convection on moist hot days. A thunderstorm is a well-grown cumulonimbus cloud producing thunder and lightning. When the clouds extend to heights where sub-zero temperature prevails, hails are formed and they come down as hailstorm.
If there is insufficient moisture, a thunderstorm can generate duststorms. A thunderstorm is characterized by intense updraft of rising warm air, which causes the clouds to grow bigger and rise to greater heights. This causes precipitation. Later, downdraft brings the cool air down to earth and the rain.
From severe thunderstorms sometimes spiralling wind descends like a trunk of an elephant with great force, with very low pressure at the centre, causing massive destruction on its way. Such a phenomenon is called a tornado. Tornadoes generally occur in middle latitudes. The tornado over the sea is called water sprout.
A mesocyclone is a dense, swirling pack of cloud and winds between half a mile to six miles wide. To the eye, it looks like a thin, vertical band of black clouds that spins from beneath thunderclouds. A mesocyclone turns into a tornado if it hits the ground and continues to churn up wet, warm air. The United States experiences approximately 1,700 mesocyclones a year, with 50 per cent of these turning into tornadoes.
v. Polar or Arctic Cyclones:
Arctic or polar cyclones occur in Antarctic regions and can reach up to 1,200 miles wide. Polar cyclones differ with others because they are not seasonal. They can occur at any time of the year, unlike in the Gulf of Mexico when during late summer, the risk of a hurricane increases.
Polar cyclones can also be formed quickly (sometimes less than 24 hours), and their direction or movement cannot be predicted. Plus, they can last from a day to several weeks. Most frequently, polar cyclones develop above northern Russia and Siberia.
vi. Other Types:
Cyclones that are in between the tropical cyclone band and polar areas have different names. For example, sub-polar or subtropical terms are used to categorize them. Typically, however, the cyclones are formed in the same way. The variables are the wind temperature, predictability and durability. Those near the Arctic Circle are colder, more unpredictable and random in movement and can last for short and very long periods of time.
Essay # 8. Vulnerability to Cyclones:
Cyclones are natural events, which can neither be wished away nor prevented. What actually makes these hazards turn into disasters is the vulnerability of the people and their means of livelihood and the fragility of infrastructure.
The Indian Sub-continent is the worst affected part in the world as far as loss of lives is concerned though more severe cyclones do occur in other parts of the world and financial losses are much more elsewhere.
High population density, comparatively better employment opportunities and economic compulsions force people to occupy areas which are susceptible to cyclones, saline ingress and flooding. Inadequacy of infrastructure adds to their vulnerability.
Traditional coping mechanisms have been the mainstay for these people to counter hazards, but during major disasters these coping mechanisms are found wanting. Though communities have a natural tendency to face hazards by joining hands, they usually fail to generate the desired synergy because of unsystematic and adhoc approaches.
On many occasions people are not even aware of the risks involved. The frequent disasters nullify the development of several years and turn the clock back for these vulnerable families.
Essay # 9. Impact of Cyclone on the Coastal Ecosystem:
‘Coastal ecosystem’ includes estuaries and coastal waters and lands located at the lower end of drainage basins, where streams and river systems meet the sea and are mixed by tides. The coastal ecosystem includes saline, brackish (mixed saline and fresh) and fresh waters, as well as coastlines and the adjacent lands. All these water and landforms interact as integrated ecological units.
Shore-lands, dunes, sandbars, offshore islands, headlands, and freshwater wetlands within estuarine drainages are included in the definition since these interrelated features are crucial to coastal fish, wildlife and their habitats. Mangroves are located all along estuarine areas, deltas, tidal creeks, mud flats, salt marshes and extend over 4871 sq. km (about 7% of world’s mangrove areas).
Impact of global warming-induced sea level rise due to thermal expansion is more pronounced in the Bay of Bengal due to the shallowness of the waters. The entire coastal ecosystem in general and the eastern coast in particular are highly vulnerable due to flat and low terrain, high population density, over-exploitation of natural resources, high rate of environmental degradation on account of pollution and non-sustainable development.
On many occasions, the livelihood requirements of people are detrimental to maintaining the delicate balance of the fragile coastal ecosystem. Degradation of the eco-system not only affects the environment adversely, but also makes the people living in the coastal areas more vulnerable.