On the chars, the flat islands in the mouth of the Bay fashioned by the ebb and flow of the tide from silt deposited into the estuary, the vast majority of inhabitants have two good options when a cyclone comes their way: evacuate, or take cover in a cyclone shelter. It is higher the more gently the continental shelf slopes away from the coast, and the more the coast is shaped like a funnel. The height of the storm surge depends on the angle at which the storm or cyclone approaches the coastline, and whether the tide is ebbing or flowing. When the wind comes to shore, however, and reaches the shallows, the water under the surface can go nowhere, but up. In the open ocean, the wind moves water in currents, underneath the surface, which may ripple with small waves. If this happens more than five hundred miles from the equator, the winds are sent spinning by the rotation of the Earth, creating a cyclone. At other times, as the ocean creates more and more warm, humid air on its surface, a chain reaction takes hold, creating a storm.
Sometimes the winds are buffeted by countervailing systems, and peter out. Over the open ocean, where there are no obstacles, the winds pick up faster. When warm ocean air rises, the air pressure on the ocean surface falls, and the winds pick up. And the oceans transfer heat, through underwater currents, and through storms and cyclones. The atmosphere transfers heat by sending cold winds from north to south, and hot winds from south to north. The teeming variety of life on Earth is made possible by the Earth’s heat transfer system. Thursday, November 12, 1970, Bay of Bengal On November 12, 1970, one such cyclone made landfall, 60 miles west of Chittagong. Once in a while, they change the course of history. Twice a year, tropical cyclones appear on the south coast of Bangladesh.
0 kommentar(er)
