'Urbanisation, tree felling leading to surge in lightning strikes'
Kolkata: Unplanned urbanisation and felling of trees were behind a recent surge in lightning strikes and the number of deaths in such incidents in the country, a meteorologist of a Pune-based institute said.
These days, lightning is more in the cities than in the rural areas of India, the senior meteorologist of the Indian Institute of Tropical Meteorology (IITM), said.
"Around 3,000 to 3,500 people die every year in the country due to lightning. But the trend is little higher since the last five years. And this year we are expecting more lightning at stations over the foothills of Himalayas (starting from Jammu and Kashmir till the Darjeeling foothills) central and eastern part of the country," scientist of the Atmospheric Electricity Aerosol Physics of the IITM, Dr S D Pawar said.
Though there is no past official record on the number of deaths because of lightning strikes in India, Dr Pawar said a study conducted by them in this connection in the last 20 years shows that it is "definitely" on the rise. He said this is a natural phenomenon. Though lightning depends mostly on the moisture content of a particular region there is no exact reason behind the recent rise of lightning. "However, urbanisation is one of the main causes behind the rise which is mostly witnessed in the metro areas," he said, adding global warming is also another reason behind the recent surge in the incidents of lightning.
He said with the cutting down of trees the city regions of India were turning into urban heat islands which is
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Elaborating the "urban heat island" concept, Dr Pawar said, that it is an effect which describes the variation in temperature between cities and their surrounding areas.
"Because of the cutting down of the trees and unplanned urbanisation, the cities are getting warmer than their rural surroundings. The temperature is rising mainly due to the highrises, roads and other infrastructure replacing open land and vegetation," the scientist said.
The scientist said, "Among other reasons pollution is definitely a factor. Apart from that carbon and dust particles in the air could also be one of reasons. And pollution is higher because in and around the city region there has been an increase of dust particles in the air."
"During the months of April-May, that in summer there are high incidence of thunderstorms. However, lightning is less during the monsoon season in June-July and number of deaths are lesser," he said.
"We have conducted a study on the spatial distribution of convective available potential energy (CAPE) and lightning activity in different seasons over the Indian region to find out the dependence of lightning activity on CAPE.
"And it is observed that the lightning activity over the Indian region is not controlled by CAPE alone during pre-monsoon season. The prevailing meteorological conditions and orography over northern India, central India, northeast Pakistan and Bangladesh provide favourable conditions for formation of thunderstorms and that's why lightning activity is higher in spite of lower value of the CAPE over these regions compared to other parts of India," Dr Pawar said.
Lightning which has become a frequent natural phenomenon during the summer, mostly in the two months of April and May, however, becomes quite irregular during the monsoon season, he said.
On whether lightning has gone up in the hilly regions in the northeastern part of the country, Dr Pawar said, "It's not that high in Shillong or in the seven northeastern states because the hills still have a green coverage."
However, in metro city like Kolkata lightning incidents are pretty higher compared to cities like Mumbai, he said.
Incidentally, Andhra Pradesh recorded 36,749 lightning strikes in just a 13-hour period in the month of May.
A home ministry data shows that till May, as many as 80 people have been killed in five states due to thunderstorms and lightning strikes with Uttar Pradesh alone recording 51 deaths, and 136 people injured across the country.
Deaths due to lightning is higher in Maharashtra mostly in Nagpur and Vidharbha, Aurangabad, in Odisha as well as in West Bengal mainly because of the instability and moisture content in the air.
"But in monsoon lightning deaths are lesser because the clouds lie at the low level. And the passing of lightning is quicker because of the shorter distance between the clouds and the ground," he explained.
The meteorologist also stressed on the need of conducting more research works in connection to understand about the character of lightning which is different in different regions of the country owing to the difference in the climatic conditions.
"Some research works are going on in different regions. But we need to conduct more studies because of the difference in their character of the weather. We must not forget that India is a vast country with absolute different climatic conditions. Study is also necessary to ascertain why it is growing these days," Dr Pawar said.
"High buildings should have lighting arresters and they should be equipped with other good technique to bypass lightning through it and reach the ground," he elaborated.
And one must lie down and should avoid movement during lightning.
"If you lie down during a thunderstorm, an electrical current passing through the ground from a nearby lightning strike can pass right through your body," he signed off.