Class 7 Science
CYCLONES AND TROPICAL CYCLONE | HOW ARE CYCLONES FORMED | CAUSES AND EFFECTS OF CYCLONES 1
How are cyclones formed | Causes and effects of cyclones What is a cyclone? A cyclone is a system of wind that moves rapidly inward with a low-pressure area in the middle. In meteorology, it refers to the large mass of air that surrounds a strong atmospheric center. The internal winds moving over an area of low pressure allow us to view the storm in a spiral shape. The large-scale (synoptic scale) polar vortex and extra-tropical cyclones are the largest low-pressure systems. The synchronous scale also includes tropical cyclones such as tropical cyclones and subtropical cyclones. 2
How are cyclones formed | Causes and effects of cyclones
How are cyclones formed? Tropical cyclones form only near the equator, in warm ocean waters. A cyclone is formed when warm, moist air near the ocean’s surface rises upward. When air rises away from the ocean’s surface, it generates a low-pressure zone beneath it. It causes air from higherpressure places to travel towards the low-pressure area, warming the air and causing it to climb above. 3
How are cyclones formed | Causes and effects of cyclones
What is a tropical cyclone? Tropical cyclones are familiar to most people because they occur in tropical oceans. Cyclones and tornadoes are actually tropical cyclones, but they have different names that indicate where the storm is occurring. Tropical cyclones only form in warm ocean waters near the equator. A hurricane forms when warm, humid air rises above the surface of the ocean. As the air rises above and above the ocean surface, it creates an area of low pressure. This causes air to move from areas of high pressure to areas of low pressure, causing the air to heat up and rise. 4
How are cyclones formed | Causes and effects of cyclones When warm and humid air rises and cools, the water in the air turns into clouds. As ocean heat and water evaporate from the surface of the ocean, the entire system of clouds and winds rotates and rises. As the air system spins at increasing speed, an eye forms in the middle. The center of the storm is very calm and clear. The difference in temperature between the warm and rising atmosphere causes the air to rise up and become more energetic. When the wind speed is 39 mph (63 km/h), it is called a “tropical storm”. When wind speeds reach 74 mph (119 km/h), the storm is officially called a “tropical cyclone” or hurricane. Every year 70 to 90 hurricane systems develop around the world. The Coriolis force causes air to spiral in a region of low pressure. Typically, cyclones occur in the Atlantic and Northeast Pacific, while they occur in the Northeast Pacific. We can define tropical cyclones on the basis of their wind rate. Cyclones are classified according to wind speed and the damage they cause.
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How are cyclones formed | Causes and effects of cyclones Category 1: Wind speed between 90 and 125 kmph, with some
damage to buildings and trees. Category II: Wind speed 125 to 164 kmph, habitat damage,
significant crop, and forest damage. Category III: Wind speed 165224 kmph, Structural damage to homes,
extensive damage to plants and uprooted trees, repaired cars, building damage. Category IV: Wind speed between 225 and 279 kilometers per hour,
with power outages and significant damage to cities and towns. Category V: Wind speed greater than 280 kmph, with extensive
damage.
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How are cyclones formed | Causes and effects of cyclones Polar Cyclone Cyclones are common in the polar regions of Greenland, Siberia, and Antarctica. Polar winds are heavier than tropical cyclones in winter. As you can see, these storm travelers love good weather! In areas of the field, they are not very common and occur only very rarely, which is why the damage they do is minimal. Mesocyclone The mesocyclone gradually moves into a vortex as part of the lightning cloud begins to spin. The ‘center’ refers to the ‘meso’, which we can consider as the midpoint between one climatic form and another. All storms are thunderstorms, but not all parts of the thunderstorm are caused by cyclones. Part of that cloud turns into a storm, even if you can’t actually see it happening, it’s an intermediate or ‘meso’ step from a normal cloud to a dangerous spinning cloud moving to the ground. 7
How are cyclones formed | Causes and effects of cyclones What are the causes and effects of cyclones? Tropical cyclones cause heavy rainfall and landslides. They cause serious damage to towns and villages. In addition, they destroy coastal companies such as shipyards and oil wells. When these storms blow in the distance, they cause great damage to human settlements. They destroy a lot of crops and a lot of forests. They disturb the entire civilian life, especially when they hit the power and telephone lines. These cyclones often cause tornadoes, which can lead toflooding. They cause great damage not only to property but also to the lives of the people. Civil institutions are being demolished
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How are cyclones formed | Causes and effects of cyclones What are the local names of cyclones? Typhoons – China Sea Tropical Cyclones – Indian Ocean Hurricanes -Caribbean Sea Tornadoes-USA Wily Willies – Northern Australia Baguio- Philippines Taifu- Japan What are the Cyclone prone areas in India? India is prone to natural calamities like earthquakes, floods, droughts, cyclones and landslides. According to the Meteorological Department, there are 13 coastal states and Union Territories of India prone to cyclones. The four states at risk are West Bengal, Andhra Pradesh, Odisha, Tamil Nadu, and one union territory on the east coast, Pondicherry, and one on the west coast, Gujarat. 9
How are cyclones formed | Causes and effects of cyclones What is the cyclone warning system in India? The Meteorological Department of India is the nodal agency in India responsible for weather monitoring, weather forecasting, and seismology. The Cyclone Warning Center (ACWC) predicts a storm area in the Bay of Bengal and the Cyclone Warning Center (CWC) in the Arabian Sea. The ACWC and CWC sent their reports to the coordinating center, National Cyclone Warning Center (NCWC). Every year, Cyclones transmit energy equivalent to several megatons of nuclear bombs from the ocean into the atmosphere. Every year 70 to 90 hurricane systems develop around the world. Cyclonic systems do not develop in this region because the Coriolis force is low between latitudes 5degrees north and 5degress south at the equator. Prepare CBSE online Class 7 with our Animated Video lectures and Interactive Online Live Classes for class 7
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