Our earth is surrounded by air that contains gas for breathing and also many other gas molecules. They protect our earth from harmful radiation and act as a blanket over the earth. It is extended to space. Atmospheric pressure is calculated by using a barometer. Because of the gravitational force of attraction, the air exerts a force upon the surface. This is called atmospheric pressure.
$$\mathrm{Generally,\: atmospheric \:pressure\: is\:P_{a}\:=\:\rho gh}$$
Disturbances that occur in the atmosphere are called atmospheric disturbances. They do not last for a long time and they move from one place to another. Even Though it has a short life it makes drastic changes in the atmosphere and leads to harsh weather conditions. Some of the atmospheric disturbances are cyclones, hurricanes, and tornadoes.
A cyclone is a large amount of air or wind that rotates in a clockwise or anticlockwise direction in the southern hemisphere or the northern hemisphere making a swirling atmosphere. In that, the center part is at low atmospheric pressure that is surrounded by high atmospheric pressure.
Cyclone is the rotation of air in the atmosphere. The cyclone’s center is called the eye of the cyclone where the pressure of the air is low. The area of this region is around 10 to 40km in diameter. There occur only light winds and mostly it has no clouds or low clouds. The cloud region that surrounds the eye is called the eye wall which has a diameter of about 150km. The speed of the wind blowing in this region is around 150 to 250 km/h which results in heavy rain. It causes maximum destruction. The eyewall is the most destructive part of the cyclone as there is a high speed of air. The clouds rise from the surface to the height of about 300m. There are also secondary cells around the center called rain bands. They are the band of clouds spiraling into the eyewall and it contains heavy rain.
Fig:1 Structure of cyclone
Cyclone is a large mass of air that originates above the water bodies in tropical regions. Tropical regions are the regions that lie between the tropic of cancer and the tropic of Capricorn near the equator. Because they are the regions that get direct solar radiation. The warm air near the surface of the ocean rises upward. So the pressure becomes low near the surface.
Air always travels from high pressure to low pressure. So the space was covered by the surrounding high-pressure air. Again the warm air rises and the surrounding cool air comes down and the cycle continues and forms clouds. This circulation of air forms the storm system. When the speed of the air is around 63kmph then it forms a tropical storm. If it reaches the maximum speed of about 119kmph it forms a cyclone. Generally, cyclones weaken when they reach land.
Cyclones are the most disastrous and most violent atmospheric disturbance.
Generally cyclones are formed during maximum solar radiation.
Average speed of the cyclone varies from 30kmph to 200kmph. Sometimes it may reach 400kmph.
Maximum they occur over water bodies like the ocean. When they reach earth it weakens.
Generally they occur during a specific period only. July to October is the period that cyclones occur in the northern hemisphere. December to March is the period that cyclones occur in the Southern hemisphere.
The cyclones are classified as
Tropical cyclones: Tropical cyclones are generally formed above the ocean. The eye of the tropical cyclone has different shapes like circular, concentric, and elliptical.
Polar cyclones: Polar cyclones are formed over polar regions.
Mesocyclone: Mesocyclones are formed due to the air rotating within the storm.
hurricane is a mass of air swirling with a speed of 119kmph or higher than that. When it reaches the earth it forms a storm surge along with heavy rainfall. Information was given by the predictors about the direction and its strength. By knowing people can prepare to handle this. according to the speed of the hurricane, it is classified as follows.
Category 1 − Hurricanes of this type have speeds of about 119-153kmph which is faster than the speed of the cheetah.
Category 2 − Hurricanes of this type have speeds of about 154-177kmph which is faster than the speed of the fastball of a baseball pitcher.
Category 3 − Hurricanes of this type have speeds of about 178-208kmph which is faster than the speed of a tennis player.
Category 4 − Hurricanes of this type have a speed of about 209-251kmph which is faster than the speed of a roller coaster.
Category 5 − Hurricanes of this type have speeds of more than 252kmph which is equal to the speed of high-speed trains.
| Cyclones | Hurricanes |
|---|---|
| Cyclones is the mass of air circulating with low pressure which is accompanied by storms. | Hurricanes are cyclones that are the mass of air swirling with a speed of 119kmph or higher than that. |
| Clockwise circulation happens in the southern hemisphere and anticlockwise circulation in the northern hemisphere. | Their clockwise circulation happens in the southern hemisphere and anticlockwise circulation in the northern hemisphere. |
| Intensity measurement is made on different scales in different countries. They are strong. | Based on Saffir-Simpson Hurricane Wind Scale it is classified into five categories. The intensity increases from category one to five. |
| They arise mostly in the Southeastern Indian ocean and Southwestern Pacific ocean. | They arise in the North Atlantic Ocean and Northeast Pacific ocean. |
| Pacific ocean regions are mostly affected by cyclones. | Caribbean sea regions are affected by Hurricanes. |
| There are around 10-14 cyclones arise per year | There are around 10-15 hurricanes that arise per year |
Cyclones are one of the atmospheric disturbances on earth. It mostly occurs over the water bodies where warm areas are located. The place of occurrence of these disturbances is different from Hurricanes. Hurricanes are classified according to their wind speed in five categories. There is only a small difference between Cyclones and Hurricanes. They were discussed in this article in detail.
Q1. What are the causes of Cyclones?
Ans. Warm temperature that occurs at the sea level, Coriolis force effect, instability in the atmosphere, increase in the humidity of the air to the upper layer, variation in the velocity of air in a vertical direction, and low-level disturbance that occur earlier are the causes of Cyclones.
Q2. What is the Coriolis effect?
Ans. A force exerted on the mass of air that is rotating in about an axis is called Coriolis force. This force acts in the direction perpendicular to the motion and to the axis of rotation. This effect is called the Coriolis effect.
Q3. Which are the cyclone Hazard zones in India?
Ans.Mostly the coastal regions are affected more by cyclones. Among the most hazardous areas are Tamilnadu, Andhra Pradesh, West Bengal, Odisha, Puducherry, and Gujarat.
Q4. Give some preventive measurements of cyclones.
Ans. Stay safely inside the house and keep away from electric mains. Make sure of a basic kit for survival. Keep noticing regular updates. In case of unsafe weather, better shift before the storm. These are the basic precautions that should be made before and during cyclones.
Q5. What are all the regional names of cyclones?
Ans. They are called by different names at different places. They are
Cyclones in Indian Ocean
Hurricanes in the Atlantic Ocean
Typhoons in Western Pacific and China Sea
Willy-willies in Australia
Taifu in Japan
Tornadoes in USA
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