The hurricanes are the strongest types of storms that cause the most loss of property and damage to mankind. The hurricanes are the natures most powerful storms and they produce strong winds, rainfall and also lead to floods.
These are dangerous storms as they combine three hazards of violent winds, very high waves and torrential rains. These have the capacity to pose a serious threat to life and property. The destruction caused by hurricanes is widespread and it results in massive losses.
Description of Hurricanes
Whether we call them Hurricanes or typhoons or cyclones they are actually the same type of storm. The names differ on the basis of the place of origin. In the central and eastern region of North Pacific, they are called “hurricanes”. The “typhoons” are the ones that occur in the western North Pacific and “cyclones” are the ones that occur in the Indian Ocean and the South Pacific.
The tropical cyclones or the “Hurricanes” are the low-pressure wind systems that form over the tropical or the subtropical waters and they get their energy from the warm ocean waters. Hurricane is a rotating low – pressure weather system that comprises of thunderstorms but without fronts i.e. a division separating the air masses with different densities.
Important Concepts of Hurricane
- Sustained Winds: Sustained wind is a common indicator of the intensity of the storm. Most of the weather agencies make use of the definitions by the World Meteorological Organization (WMO). But the United States Weather Service has its own definition and uses the same.
- Eye: The centre of the hurricane is the eye. The eye is the area of very low air pressure. There are no clouds present in the eye and the wind is calm. The eye is the most dangerous part of the storm.
- Rainbands – Hurricanes have large spiral bands of rains that can drop a huge amount of rainfall that can cause floods when it hits the land.
- Diameter – The diameter of a hurricane can span over 600 miles. We measure it from one side to the other.
- Height – the height of a powerful Hurricane can reach up to nine miles in the atmosphere.
Formation of Hurricanes
Hurricanes or the Tropical cyclones work like huge gigantic engines that make fuel from warm and moist air. Therefore these tropical cyclones form over the warm water oceans near the equator. The process is, the moist air from the warm water oceans rises up and as this air rises up and moves towards the surface less air is left near the surface. This causes an area of lower pressure below.
The air from the nearby areas along with higher pressure exerts pressure and pushes in the low-pressure area. Now, the “new” air naturally becomes warm and moist and rises to. Here, the new air refers to the air that has pushed itself in the low-pressure area. The warm air continues to rise. Hence the surrounding cool air swirls in to take its place. And clouds are formed as the moist air rises and cools off. The entire system of clods and winds grows and spins as the ocean’s heat and water evaporate from the surface.
It also needs to be understood that the storms north of the equator spin anticlockwise and the storms south to the equator spin clockwise. This phenomenon occurs because of the Earth’s rotation on its axis. Now, as the storm system gains speed an eye is formed in the centre of the storm. As the wind in the rotating storm reaches 39mph the storm is termed as a “tropical storm”. And as the speed of the storm reaches 74mph it officially becomes a “Hurricane”.
As the tropical cyclone hits the land it becomes weak because no longer the energy of the warm ocean water reaches them. The storm then more than often moves to the far inland causing heavy rains and wind damages before it finally subsides or dies out.
Categories of Hurricanes
Depending upon the wind speed of the storm, we can classify the Hurricanes as follows:
- When the wind speed is between 74 to 95 mph and the storm surge is 4 to 5 feet, it causes minimal damage to the land. This falls in category 1.
- When the wind speed is 96 to 110 mph and the storm surge is 6 to 8 feet, it causes moderate damage to the land. This falls in category 2.
- Category 3 is when the wind speed is 111 to 129 mph and the storm surge is 9 to 12 feet, it causes extensive damage to the land.
- When the wind speed is 130 to 156 mph and the storm surge is 13 to 18 feet, it causes extreme damage to the land. This falls in category 4.
- When the wind speed is 157 mph or higher and the storm surge is 19+ feet, it causes catastrophic damage to the land. This falls in category 5.
Q.1.What are tropical cyclones?
Answer. Hurricanes, typhoons and tropical storms are classified as tropical cyclones. These cyclones usually form in the hot oceans and in areas of low pressure.
Q.2. How are hurricanes formed?
Answer. When Warm Ocean waters combine with the heat of the surface and begin to rise it produces a low pressure on the sea surface of the water. Thus, air begins to rise. The low pressure hence created makes the winds circulate in opposite directions and cause winds to spin. The process is repeated and it causes the air to rise faster and faster and attract more warm air from the sea surface and absorb cooler and drier air from the upper layers. The wind speed increases and the air is sucked by the low-pressure centre.
Q.3. What is an eye of the Hurricane?
Answer. An eye is a circular area that contains the comparatively lighter winds. Even though the winds are calm at the axis of rotation, the strong winds may extend well into the eye. The blue sky can be seen through the eye.
Q.4. What makes Hurricanes dangerous?
Answer. The hurricane that hit Galveston in 1900 resulted in almost death of 6000 people and the entire city was devastated. The Mississippi coast witnessed hurricane Camille in 1969 and it killed approximately 262 persons and caused damage of nearly $1 billion. Due to the implementation of the warning systems, the losses in the recent hurricanes have been less as compared to the earlier ones.
Q.5. Why names are given to hurricanes?
Answer. A hurricane is given a proper name so that it becomes easy to remember the tropical storm. It is easier to remember the name of the storm and track it by using the latitudinal and longitudinal coordinates. Another reason for naming the hurricanes is that it prevents the confusions when there is a possibility of having more than one tropical storm or hurricane occurring at the same time. Hence a proper distinguishing name is given to the hurricanes.