The triumphant tropical storm


By Hiya Islam


Hurricanes, typhoons and cyclones are some of the triumphant natural phenomena. We have all heard of them. These are in fact the same thing and are collectively known as the tropical storms. Their names vary with the region of formation. If formed in the Atlantic Ocean or eastern Pacific Ocean, they are called hurricanes. Storms arising from the Indian Ocean or South Pacific are cyclones while the ones emerging in Southeast Asia or Northwest Pacific are typhoons.

There are four stages in the development of a tropical cyclone. Tropical disturbance, tropical depression is followed by tropical storm and tropical cyclone or hurricane. Warm, humid air above the ocean surface rises due to convection creating an area of low pressure below. Surrounding air takes up its space and becomes warm and moist. It rises again. As it rises, water vapor in the air condenses to form clouds. Soon a system of clouds and winds starts to whirl. A hurricane at its infancy is known as a tropical disturbance. When the winds are moving at 25-38 mph, the storm is now called tropical depression. As soon as 39 mph is reached, it becomes tropical storm. At this point, it is given a name. As the cycle of evaporation and condensation continues, the thunderstorm gets bigger and faster. When wind speed hits 74 mph, the storm matures into a hurricane. The Saffir-Simpson hurricane wind scale categorises hurricanes depending on wind speed and the ability to destruct. There are 5 categories: category 1 (74-95 mph), category 2 (96-110 mph), category 3 (111-130 mph), category 4 (131-155 mph) and category 5 (155+ mph). From categories 1 to 5, the extent of damage a hurricane can cause increases substantially. The damage done by a hurricane is mainly due to high winds, rainfall and storm surge. Hurricanes, when in land, gradually weaken in strength as the source of energy from hot waters is cut off.

A hurricane has several parts to it. At the center of the storm is the eye. The whole storm revolves around it; clockwise rotation in southern hemisphere and anti-clockwise rotation in northern hemisphere of the earth. In this region, the skies are clear and the air pressure is low. The eye wall, on the other hand, surrounds the eye and has winds of the greatest speed and the most damaging rains. And rainbands, which are the spiraling clouds that cause heavy rainfall.

Meteorology is the branch of science that deals with the study of atmosphere and weather. Meteorologists of WMO-World Meteorological Organisation, have made a list of 21 names for each year in specific order till 2022. This list consists of both male and female names. The names are given in the order assigned. Some names for instance, Matthew, Katrina, Sandy will not be used again as they have been particularly deadly and caused massive financial losses.


Hiya Islam is a student of BRAC University.


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