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On March 19, a tornado hit the outskirts of Sialkot. People in Pakistan are familiar with other forms of storms that unleash energy while moving along the earth’s surface. This particular lightning storm was a special type of tornado – more specifically, a twister. In this part of the world, only a few are familiar with the word twister whereas these are quite commonly known in North America. Loss of property and life is often reported on account of twisters and other similar disasters such as whirlwinds, hurricanes, cyclones, tornadoes and such.
Generally, the two words are used interchangeably but now, the synonymic status has been altered because of deeper insight into its forms, size, area affected, terrain, underlying mechanism and its varying intensity.
A tornado (wrongly considered the same as a twister) is a storm covering a wider area and lasts a longer duration. In case it occurs over a smaller area, on a body of water it is known as ‘waterspout’. The same thing on a large body of water, for instance the sea or ocean, is known as a ‘cyclone’ in Asia-Pacific and a ‘hurricane’ in the US. The winds within a severe cyclone gusting around a moving centre on earth or a water surface, may attain a speed of 350 km/hour or even more. On its landfall, it may have a very damaging effect.
The difference between a tornado and a twister has now become more pronounced and it is appropriate to restrict the term twister to tornadoes that have a very strong upward component of whirlwind, having a tendency of lifting, uprooting and hurling objects on ground. Therefore, a tornado may become a twister as soon as it has achieved a classifiable destructive ability. In reality however, a twister is generally supposed to reside in the wobbling axial hyperactivity within a tornado and shows itself up when associated parameters acquire specific criticality. The deadliest twister in history killed 625 and injured more than 2,000 people.
The development of a tornado is easily explainable with the help of wind velocity, pressure gradients and the curl vectors but how it morphs into a twister is a phenomenon that is still under study. A tornado per se is preceded by a lashing windstorm, rain, hailstorm and a thunderstorm. For allowing it to grow into a twister, it has to have an upper layer of icy cold wind with hot air underneath. The two interact, causing an increase in wind velocity, producing curly gusts. This sets in spiraling of air with higher velocity as the hot air converging near the earth’s surface is sucked upwards. Latent heat from icy droplets being pulled downwards mainly under the influence of gravity is pumped in as additional energy to it and the twister becomes more violent.
At times, a hailstorm may also compound the problem. Within minutes, it becomes a monster in its own way. Statistically, very strong storms are only around one per cent of total recorded tornadoes (including twisters). This assessment is dependent upon the areas where damage may be high or relatively less, inducing error in its classification. Thus a twister intensifying and then devastating the sub-urban, non-residential area would have lesser ratings than if it were to strike over an urban residential path.
With the changing weather patterns, Pakistan has started getting its share of twisters. The recent tragedy experienced by the people of Sialkot bears testimony. Historically, there are very few such tornadoes reported in the country before that. In 1981, Gujranwala and Sheikhupura areas were ravaged with 56 deaths and 600 injured. Similar calamities hit in 1985, 1995, 2001 and 2006 in different parts of the country causing loss of life and property. But now twisters are becoming a frequent phenomenon and public awareness in this regard is of paramount importance despite the fact that people often come across dust storms in the plains and lightning storms in hilly areas.
In the present information age, reporting and some elementary steps are being taken, but the need to do better, at a bigger scale and with much more zeal has become an essential requirement. Continuing within existing resources, immediate steps can reduce the damage primarily due to its randomness, suddenness and subsequent ill-preparedness of the rescue units.
Data shows that winters in the country are shortening. This will continue to happen until the normal cooling pattern on earth is restored. That will render northern part of Punjab and western part of Khyber-Pakhtunkhwa prone to twisters in the days to come. Critical period of occurrence is likely to be in March and April. Thus, Gilgit, Havelian, Haripur, Taxila, Mardan, Islamabad, Kohat, Mandi Bahauddin, Jhelum, Gujrat, Sialkot and places around Quetta are likely to become more vulnerable. The reason behind this assertion is that there is increased likelihood of having warm air below a suddenly appearing cool layer of moisture-laden air (leading towards formation of a super-cell). So, it will be disservice to the residents of these areas if proper timely information is not passed on to them. In addition, well-documented safety precautions such as moving into safe zones and to avoid injury through electric wires should be made handy through all relevant means.
It is suggested that a home-grown classification of such storms, based on its severity, be worked upon to replace the Fujita method. Pakistan is facing host of problems and the people are paying huge cost for inefficiency and un-professionalism. Not all are to be blamed; there are many who want to contribute. Thus, here is an opportunity for hard-working and honest people to serve the nation through their efforts towards alleviation of the some of the sufferings of the poor through effective disaster management.
The writer is a retired Chief Engineer PTCL and a radio engineer with special interest in ionospheric and tropospheric composition as well as climatology.
