Hurricane is again in the news with hurricane 'Irene' striking US coast. In that background let us see some aspects of Hurricanes.
What are Hurricanes?
Hurricanes are tropical cyclones with a wind speed of about 119 kmph. In our country we are familiar with cyclones, as many times our country's east coast has been subjected to vast damages and human losses. As Cyclones originate in tropical areas they are called Tropical cyclones. Tropical cyclones occur due to the reasons of pressure drop due to the warming up of ocean water. The warm air over the warm waters cause a low pressure zone and makes a dangerous whirl of air, water and waves gushing in and spiraling due to the pressure drop. This rises up as a violent spiral upwards drawing thunderstorms and high speed winds. The cyclone then drifts over sea in anti clockwise swirls and may become more fast and virulent and may cross land at some coast. Gradually it becomes weak. But by this time it would have caused havoc by heavy winds, rains and thunderstorms. The birth of cyclones happen when the conditions for low pressure and whirl like temperature difference, low winds etc exist and develop gradually. Cyclones with (sustained) wind speed of 74 miles per hour (119 mph) originating in Atlantic Ocean are termed Hurricanes.
Why and How Hurricanes are named
On an average ten to twelve cyclones occur in Atlantic Ocean in a year. Many of them stay in ocean itself. About half of them or there develop into Hurricanes and maybe one or two strike at the US coastline. They cause damages and loss of life in varying degrees.
In order to identify and for statistical purposes, the hurricanes (or cyclones) are named. The naming is decided by the World Meteorological Organisation or the National Weather Offices of the region. Thus the list of names is different for different regions. The names are prepared in advance for a full year in alphabetical order alternating in female and male names. For the North Atlantic region for 2011 it started with Arlene and the present one is the ninth one of the year called Hurricane Irene, in the alphabetical order. Next in list is Jose. For the North Indian Ocean Region which is monitored by Meteorological centre, New Delhi, the first cyclone in 2011 was Keila from the list available.
Body structure of a Hurricane
A hurricane will be occupying a circular whirl area of 10 to 150 km diameter. The central area varying from 10 to 50 km is called 'eye' and is a cloud free area. Surrounding the eye is the eye wall cloud area ranging fro 50 to 150 km which will involve strong winds and torrential rains. The upward height of a hurricane may be about 15 km. Hurricanes can vary in size and even have 150km to 800 km and move at a rate of 300to 500km a day over sea. In the northern hemisphere, the hurricanes move northward in anti-clockwise direction.
Though hurricanes can occur anytime, the Hurricane season is May to November.
Category of Hurricanes by strength
Basing on the strength Hurricanes are categorized as Category I to category 5 in the Saffir-Simpson Hurricane Scale. Category I denotes the weakest and category 5 is the strongest.
Hurricane Irene –August 2011
Hurricane Irene has just struck US, and has caused damages. The full reports are coming and rescue and recovery operations are going on. But it is felt that worst is over.
When the present hurricane Irene was nearing US, people could not forget the 2005 Katrina, which was devastating. Hence, though Irene is lesser in strength people are taking all precautions. However Irene is bigger in size those than typical hurricanes which is causing worry. As a precaution, the 636 megawatt, Oyster Creek Nuclear Plant ( New Jersey) is closed. New York subways are closed and about 9000 flights are cancelled. Hurricane Irene has caused death of 15 people in US as of Sunday.
In Washington DC 36000 homes were without power.
Tracking and warning of a Hurricane
Observations of various meteorological parameters of wind speed, temperature, pressure are being monitored and recorded at various intervals from land and ships. Additional data are obtained from reconnaissance aircraft and weather satellite imaging and radar. There are Automated Surface Observation systems which also monitor hurricanes.
Once a formation of a hurricane is observed, it is constantly tracked and alert advisory is given 48 hours before probable strike, over public media and enable people in vulnerable areas to prepare themselves for an eventuality of the hurricane hitting their area. A hurricane can cause torrential rains, flooding high speed wins, surge of waves etc. The alert is revised to warning before 36 hours of probable arrival and if needed evacuation is advised. People are given awareness to take all precautions and survival measures like stocking of food and water, emergency medicines, torch etc. Public utility systems and rescue and relief systems are also placed for ready deployment.
How to tackle Hurricanes
Hurricanes possess tremendous energy and force and hence cannot be resisted though theoretically some stopping measures are tried. The best way is to cope with them by taking precautions and survival measures. As the probable vulnerable areas are coastline areas, the construction methods can be made and adapted to construct buildings and public shelters which can withstand hurricanes and cyclones.
It is nearly nine years since this article was posted. However, the article is still relevant as Cyclones, Typhoons and Hurricanes are regular happenings. Now when I am posting this comment, a Tropical cyclone 'Amphan'(pronounced as Um-Pun) is lashing the eastern coasts of India.
During the last nine years since the article, Meteorological warnings have become more accurate and governments have put in place good disaster management systems. That has helped save lives. That is always the first priority. Then comes reducing the impact on assets and economy to the maximum possible extent.
The article concludes saying "The best way is to cope with them by taking precautions and survival measures. As the most vulnerable areas are coastline areas, the construction methods can be made and adapted to construct buildings and public shelters which can withstand hurricanes and cyclones".
Though a lot has been done in this regard, a lot more remains to be done. Hope the governments, scientists and technologists and people, all will bestow their attention to this.
The article written by the author provides detailed information regarding the origin of hurricanes, its warning signs and the different tools to dilute its effect.
Our overall priority should be to save the structures erected on such areas in the form of buildings with the addition of chemicals to reinforce their strength so as to neutralise the vast force of the cyclone. The base structure of the building should be well below the ground level so as to withstand the enormous pressure of the cyclone exerted on the various components of the structure. The cost may escalate a little more with the consideration of such parameters but that is the only way to withstand such heavy impacts arising due to severe wind pressure of the cyclone.
A very informative article given by the author. Hot, humid air is required as fuel for the operation of hurricanes. Sometimes they hit the coast. When Hurricanes reach the ground, they push the seawater towards the coast. This storm takes the form of big waves ahead which is quite destructive. When a hurricane hits the waves as a storm, a flood-like situation arises. Meteorologists make predictions about hurricanes as well as predict how powerful and destructive it will be. Due to this information, people become alert and migrate to safe places. Due to this, there is less damage to human life and the surrounding ecosystem.
There is a possibility that hurricanes may come once or more, so they are named. With the help of these names, hurricanes can be tracked and information can be obtained about them. A hurricane is named when it is formed as a tropical storm and is known as Hurricane. There are six lists of names. If a storm causes a lot of damage, its name is sometimes removed from the list. It is then replaced with a new name that begins with the same letter.