Feb 05, 2023
Feb 05, 2023
Last year, these days in October, we were still smarting under the impact of Kedaranath tragedy, when a remarkable thing happened, may be for the first time in our country! A powerful Cyclone ‘Phailin’ struck the Odisha coast and the damage was more than Rs 3000 crores. But the amazing thing was that only 43 persons died. In 1999, a similar cyclone had struck Odisha coast killing more than 10000 people and rendering many more thousand homeless. This difference in the number of casualties was due to tremendous improvement in the quality of meteorological forecasts in the country and also due to the promptness of Odisha government in evacuating more than 700000 people from the rural coastal areas and to shift them to storm shelters in safer areas. The best part of the preparation was that when the people were shifted as many numbers of food packets were already available for them and the camps were well lit with all facilities.
Our ancestors compared a cyclone with the coils of s serpent. They lived close to the nature and saw the cyclones hit the sea and carry its waves up in the air like coils of a serpent and hence termed the phenomenon as Cyclone (Greek=Cyclos=coils of a serpent). Cyclones and Hurricanes are two most hazardous atmospheric systems in terms of their killing capacity.
The center of the cyclone, known as the ‘Eye’ is an area of intense low pressure. From there the pressure rises outwards. It is the wall of the storm that causes maximum damage. It is the amount of pressure drop at the centre and the speed with which it rises towards periphery, decides the intensity of the storm. On the basis of wind speeds, the storms/cyclones have been divided in to seven categories by India Meteorological Department. The super cyclonic storm rages the coastal regions with wind velocities above 222 km per hour. At this blinding speed, the storm spares none-it can not see, because its ‘eye’ is covered by the walls. Thus while the eye of the storm feels nothing, the peripheral parts create havoc.
A severe cyclonic storm is so powerful that it can create storms of 50-60 km per hour in reaches up to 600 km from the ‘eye’. While rushing through the surface of the sea a cyclone can raise waves from 3 to 20 m height. The roar is deafening, accompanied by shrieking lightening. After hitting the ground, the cyclone normally dies out within 24 hours. However, in rare cases it travels back to the sea and becomes a ferocious storm again. This is what happened in 1999. A cyclone hit the Odisha coast and after few hours it managed to take a U turn and go back to the sea. It gathered more power from there and came back to hit again the land causing more than 10000 deaths.
It is astonishing to note that out of 80 tropical cyclones that are born every year in the oceans globally 6.5% originate in the Bay of Bengal. Annually, on an average, about five to six cyclones originate in the Bay and in the Arabian Sea. O.P. Singh, and his colleagues T.M.A. Khan and Md. Sazedur Rahman of SAARC Meteorological Research Centre, Bangladesh carried out a research on past cyclones in Bangladesh and neighboring countries. They studied the data of 122 years (1877-1998) recorded history of all the tropical cyclones in the region. They found that the frequency of tropical cyclones in the north Indian Ocean has registered an increasing trend during the months of November and May. The intensification of rate of cyclonic disturbances to severe cyclones has shown an increase of 20% per 100 years during the month of November. They also observed that while the tropical cyclone frequency in this region is diminished considerably during June to September. The annual frequency of tropical cyclones in the north Indian Ocean has registered a decreasing trend of about 15% per hundred years. A statistical count of cyclones generated along the Indian coast and its surrounding areas on an average per year get 594 cyclones on the east coast compared to 172 on the west coast.
Storm surges are sometimes worst than the cyclone as the later comes and passes off, but the storm surges carry the sea water and dump it on the coast. They are generated by the winds and atmospheric pressure changes within the cyclones. In the low altitude land-locked areas like the Bay of Bengal the tropical cyclones are the major cause of storm surges. Increase in the Sea surface temperature (SST) causes greater convective activity, leading to an increased wind speed. Stronger winds and low pressures lead to stronger storm surges. Enhancement of SST in the Bay of Bengal therefore, could be as good as an open invitation for a tropical cyclone with strong storm surges. A classical example of ancient storm surge was noted by this author in Kashmir, at Pahalgam, a famous tourist spot. A rock exposure there showed crushed fragments of fossils, about 250 million year old. Indicating that long before we came in to being our our cars or industries developed, we used to get much worse cyclones. There are geological records of similar cyclones from coasts some 55 million years ago.
Some people feel that the storms have become more killer than before. It is not so. They were killers and they will remain so. It is we, who have started building habitats in their path. Naturally a habitat at such a wrong place would be devastated in a jiffy.
Well Hudhud is on way and likely strike the Odisha coast on October 12. Let us see how much the government is prepared this time!
More by : V. K. Joshi (Bijji)