The unabated heat wave has claimed more than 1,000 lives in Andhra Pradesh. Chennai recorded the highest temperature in 90 years and eight districts in Orissa had the mercury hovering above 45 degrees today. Last year as well as this year, the temperatures are almost 9-10 degrees above normal in Orissa, Andhra Pradesh and Tamil Nadu.According to the relief commissioner’s office in Hyderabad, the drought-affected district of Nalgonda accounted for the maximum number of 192 deaths, followed by East Godavari (152), Guntur (138) and West Godavari (130).Ironically, the areas most blighted are a few kilometres away from the sea. The question that everybody is asking is whether this is unusual for a country that is known for the vagaries of weather.The met department says this heat wave in the past two years is unusual but can be explained: the trough or low-pressure area that is supposed to form over land in the peninsular coast was absent last year as well as this year. It has moved slightly eastwards into the sea.Because of its absence, the life-saving sea breeze that normally hits these coastal areas by mid-day is completely absent. Coupled with high humidity, this heat becomes deadly. ‘‘People in Rajasthan and Gujarat are used to these temperatures, people here are not; hence the large number of deaths,’’ said H R Hatwar, deputy director general, Indian Meteorological Department(IMD).This is how it works: The hot winds from the hot desert plains of Rajasthan and central India flow into the peninsular region in May-June.Normally, a north-south trough through Jharkhand, Chhattisgarh and peninsular India helps in attracting north-westerly winds that have collecting moisture from the Bay of Bengal. The result is a cool sea breeze by mid-afternoon negating the effect of the hot winds from the drylands of Central India.For the past two years, this trough is absent, resulting in hot winds flowing over land, adding to the pressure of the area.The weathermen have no explanations yet about why this trough has not been forming and say it is because of certain ‘‘wind patterns’’ and ‘‘upper air dynamics’’ in the atmosphere. They are yet to see whether this phenomenon occurred in previous decades. The good news is that the trough is finally shifting towards land over the past couple of days.The much awaited monsoon that will bring relief is already late by a week as it has not yet hit the Kerala coast though it reached the Arabian Sea before schedule.But there is some good news — there has been some build-up of clouds over the past couple of days near the Kerala coast, signalling a build-up of the monsoon. The National Centre for Medium Range Weather Forecasting has predicted that it will strike the Kerala coast by the fifth of this month.The IMD has already predicted a near-normal monsoon for this season but will be giving another update in July.
