Use of surface observation data. D) low pressure areas that form over oceans,then move onshore of the lee side of the coastline. They may change their direction of movement towards north. which is asked in a various exam like UPSC IFS and other forest service examination. Cyclogenesis is the development or strengthening of cyclonic circulation in the atmosphere (a low-pressure area). This where Vol is the volume of water transported during time interval ∆t, ∆y is a unit of length of coastline parallel to the mean wind, V is the wind speed near the surface (actually at 10 m above the surface), C D is the drag coefficient, f c is the Coriolis parameter, ρ air = … Hurricanes and other tropical cyclones move at the speed of the prevailing winds, typically 10-20 mph (16-32 km/h) in the tropics. Warm air starts to move northward. The longest being Hurricane Ginger (1971) that lasted for 30 days. storm by increasing the diameter of this storm. Cyclogenesis is an umbrella term for at least three different processes, all of which result in the development of some sort of cyclone, and at any size from the microscale to the synoptic scale.. Sea surface temperature (SST) (or ocean surface temperature) is the water temperature close to the ocean's surface. Once the winds reach a certain speed, it then becomes a tropical cyclone. The meandering about the mean path occurs with a period of about 25 hours, which seems to be due to the Magnus effect suggested by Yeh (1950). The formation of a tropical cyclone requires a number of favourable environmental conditions and one of them is a suitable latitude.  Almost all tropical cyclones form over regions more than 5 degrees of latitude away from the Equator and very few occur near the Equator.  To explain why this happens, we need to first understand which forces in the atmosphere are critical to the formation of tropical cyclones.  There are three such forces including the frictional force, pressure gradient force and Coriolis force due to the Earth's rotation.  The characteristics of these three forces are introduced below: Figure 1 Moving air stream deflected to the right in the Northern Hemisphere, Figure 2 Moving air stream deflected to the left in the Southern Hemisphere, We all know that the air pressure decreases as we move towards the centre of an area of low pressure.  If there were only pressure gradient force and frictional force in the atmosphere, the air would just flow from the surroundings of higher pressure to the centre of the low pressure without any rotation (see Figure 3).  However, in the presence of Coriolis force, the air will not just move from the surroundings towards the centre of the low pressure, but will also be deflected leading to the formation of a vortex (see Figure 4), which is favourable to tropical cyclone formation.Â, Figure 3 Air streams moving perpendicularly across the centre of low pressure, Figure 4 Air streams moving to the centre of low pressure following helical paths in the Northern Hemisphere. The swift movement of the falling water droplets along with the rising air create lightning and sound. drops with increasing altitude. A series of 85-GHz Special Sensor Microwave Imager (SSM/I) images show the continued presence of an eye after Abigail passed Halls Creek, consistent with reintensification of the cyclone. Cyclones are characterized by inward spiraling winds that rotate about a zone of low pressure. 3) The cold air mass moves faster than the warm air mass. FREE Living Science 2019 2020 for class 7 Science, Chapter 15 - Winds, Storms And Cyclones from (Living Science 2019 2020). Tropical cyclones are violent storms that originate over oceans in tropical areas and move over to the coastal areas bringing about the large scale of destruction caused by violent winds, very heavy rainfall and storm surges. 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