A disastrous natural calamity, a cyclone is a vigorous aerial circulation of wind, formed over an ocean or sea.
Cyclones are powerful curling winds which arise where the atmospheric pressure is low.
These strong whistling and howling winds are accompanied by heavy rains, causing massive destruction. Cyclones, typhoons, and hurricanes are periodic tropical storms blowing in different hemispheres.
While cyclones are found in the southern hemisphere, and blow in a clockwise direction, typhoons and hurricanes are their equivalent in the northern hemisphere, but blow in an anti-clockwise direction.
Cyclones are storms that form over the Indian Ocean and the South Pacific Ocean. When these storms form over the Atlantic Ocean, they are termed as hurricanes, and when they form over the northwestern part of the Pacific Ocean, they are called typhoons.
The cyclone season is during November to April, though cyclones could strike in the month of May as well. These storms have no fixed duration, and may last just for a day, or, at times, even for a month. However, the average duration of a cyclone is about a week.
Formation of a Cyclone
The development and advancement of a cyclone is termed as cyclogenesis. A cyclone is formed by factors like warm sea water, unstable atmospheric pressure, humidity, and the wind.
Warm oceans or seas cause the air over it to heat due to the sun. When the temperature of the ocean or sea water is above 26.5 degrees Celsius, it aids this air to rise. This leaves less air near the water surface, thereby creating a low pressure area.
The rising warm air creates a vacuum and helps the cool air from the high pressure area jet into the vacant space. As soon as the air rises, it is burdened with moisture and the moisture in the air condenses to form thunderclouds.
As the Earth is constantly rotating, the air spirals at a massive speed. The winding of the air becomes aggressive and faster, creating a gigantic circle that can circulate and cause destruction.
Important Aspects of a Cyclone
Cyclones initially blow at low speeds. However, once they gather momentum, winds can blow up to speeds in excess of 175 miles per hour. The innermost area, that is the central area of the cyclone, is termed as the eye of the cyclone.
The eye of the cyclone is extremely quiet, undisturbed, and bright. The regions falling under the eye of the cyclone do not experience strong winds and heavy rains. Regions surrounding the eye, however, are drastically affected. These regions experience powerful winds and torrential rains. Areas about 12-19 miles from the eye of the cyclone are affected.
To be termed cyclonic, winds must travel at a speed of at least 75 miles per hour. Reports and studies reveal that around two million tones of air per second gushes out of a fully formed cyclone.
Categorization of Cyclones
Cyclones are categorized either by the intensity or speed of the cyclonic winds, or by a name.
According to Intensity
When categorized according to the intensity, there are five levels that a cyclone can be classified under, which are:
Category 1 A category 1 cyclone is a weak or a mild cyclone, where winds blow at speeds of 39-54 miles per hour. A category 1 cyclone causes minimal damage, with usually no major casualties. Cyclone Beryl and Cyclone Thane are some examples of category 1 cyclones.
Category 2 When the wind speed reaches between 55-74 miles per hour, the cyclone is classified as a Category 2 cyclone. Such cyclones cause damage to houses, trees, and crops. Examples of category 2 cyclones are Cyclone Emily and Cyclone Laila.
Category 3 Category 3 cyclones are dangerous, and cause losses to human life, animals, and vegetation alike. In addition, wind speeds move up to the 75-98 miles per hour range, causing serious power outages. Cyclone Winifred and Cyclone Justin are regarded as category 3 cyclones.
Category 4 When winds cross the 100 miles per hour mark, the cyclone is termed as a Category 4 cyclone. In addition to the dangers of a Category 3 cyclone, sever structural damage is experienced in a Category 4 cyclone. Examples of a category 4 cyclone are Cyclone Tracy and Cyclone Larry.
Category 5 Category 5 is reserved for cyclones that have wind speeds in excess of 128 miles per hour. A category 5 cyclone causes extreme devastation. Entire economies suffer setbacks and complete infrastructure is damaged. Cyclone Yasi and Cyclone George can be called category 5 cyclones.
According to Name
As mentioned earlier, cyclones can last for a day, or for weeks or months. There also arises a chance of more than one cyclone occurring at a time. Hence cyclones are named for identification. While cyclones were only given female names earlier (Nilam, Sally, Anne), male names (George, Chris, Tom, Michael) are also used now.
Names are assigned with respect to the region of occurrence and the speed of the cyclone. One of the main reasons of naming the cyclones is for quick identification so as to have no confusion among the weather forecasters when warnings are issued.
Some of the names forecasted for 2018 are: Alberto, Beryl, Chris, Debby, Ernesto, Florence, Gordon, Helene, Isaac, Joyce, Kirk, Leslie, Michael, Nadine, Oscar, Patty, Rafael, Sarah, Tony, Valarie, William.
Factors Causing Cyclone Destruction
A cyclone has the capability to ruin an entire habitat of a country. Cyclone devastation is usually caused by violent winds, and unmanageable downpour, leading to a host of other problems.
Wind Winds are the main reason a cyclone causes so much damage. Winds in excess of 37 miles per hour can cause damage, and are viewed as a sign of danger. If the wind speed increases, there are chances of loss of human life, and destruction to infrastructure.
Rain The moisture formed by cyclones over warm oceans can cause heavy rainfall. Continuous rains can lead to flooding. This, in turn, can lead to landslides, causing severe damage to life and property. The region becomes isolated from the rest of the world with all means of communication taking a backseat.
Coastal regions are mostly affected by cyclones, with global warming only adding to the trouble. Sea levels rise because the glaciers melt, thereby resulting in storm surges. Heavy rains result in flooding, leading to damage and destruction to mankind, vegetation, and animals living in coastal areas.
Scientific studies and workshops are carried out to find the connection between global warming and cyclones. Scientists believe that the speed of cyclones have changed dramatically over the last few decades. Hence, meteorological departments around the globe are facing difficulties in establishing accurate trends of cyclones.
Immense damage is caused by cyclones, disrupting the country's infrastructure. Many times the destruction is so severe that even the most developed and powerful economies of the world suffer a huge setback.
Preventing a natural calamity like a cyclone is not within our reach. However, by being environment friendly, and discarding deforestation and emission of poisonous gases, we can go a long way in reducing the severity of cyclones.