Cold takes south India by surprise

Could be due to cold winds from north India or Arctic Oscillation

By Dinsa Sachan
Published: Friday 20 January 2012

Southern parts of the country have been hit by an unexpected and unprecedented drop in temperatures.

While the government has not confirmed this, media reports claim that several people have died of the cold in Andhra Pradesh. Hyderabad saw a decline of four degrees in its maximum temperature, while its minimum temperature dropped by 2°C.

On January 18, Bengaluru recorded a maximum temperature of 30°C, which was three degree below normal. The minimum temperature in the city was 13°C, a three degree dip. Similarly, Chennai registered a three-degree reduction in its minimum temperature–17.7°C–on January 17. India Meteorological Department (IMD) Chennai, however, says though they have not looked at past drops, this certainly is one of the lowest temperature recorded in several years. The cold is, however, within bearable limits, they add and no deaths have been reported. “There has been no significant change in maximum temperature in the city,” says S R Ramanan, director of IMD Chennai. He adds that parts of Tamil Nadu in the northern part had registered a drop of 5°C, but weather was quite predictable elsewhere in the state. At around 8°C, Mysore recorded its coldest day on January 19.

Nothing new about it

Ajit Tyagi, director general of IMD, maintains that there is nothing special about this phenomenon. “Usually, the warm oceanic waves from the Bay of Bengal keep the peninsular region warm. But their absence because of lack of cyclonic activity over the water body has caused cold winds from the northern part of the country to fill in the vacuum over peninsular India,” he adds.

M Rajeevan, senior scientist at the National Atmospheric Research Laboratory in Tirupati, concurs. He adds that the current atmospheric conditions in the peninsular region are conducive for this sort of weather variation. “The sky is clear and the air is dry. In these conditions, lower surface air can cool to a great extent,” he says. Rajeevan accepts that this sort of temperature dip is unusual for the peninsular region. “However, this is a natural variation, and doesn’t qualify as an extreme weather event.” Rajeevan adds that a weather circulation pattern called Arctic Oscillation, an atmospheric circulation pattern in which the atmospheric pressure over the Polar Regions varies in opposition with that over middle latitudes, has caused severe cold conditions throughout the world, and it is possible its impact is just spilling over to southern India too. Met officials are unsure how long the cold-wave like conditions will persist across the region.

Gopal Dabade, public health activist who runs a non-profit called Jagruti in Karnataka, says, “The cold has taken everyone by surprise. It is unlike anything seen in the recent years. People are unprepared for it. The homeless on the streets are most affected.” Unlike Delhi, there are also no provisions to distribute blankets to the homeless, he adds.

Will it affect health?

Anumita Roychowdhury, head of the air pollution and clean transportation programme at the Delhi based non-profit Centre for Science and Environment, says, “This climatic variation could impact the pollution problem in south India, where cities are becoming increasingly polluted. Normally during cold weather, calm wind prevails and air doesn’t disperse as rapidly. Air is stationery and dense. As a result pollutants build up close to the ground level.”

A K Sharma, professor of community medicine at University College of Medical Sciences, Delhi, says it’s unclear what specific health problems the weather change might create for people. “Generally, winter triggers two types of health problems in adults–respiratory and gastrointestinal. Chronic lung diseases may be exaggerated and asthma attacks may become more frequent. The weather could also trigger acute respiratory infection in children. If anything other than this is noticed, epidemiological studies should be conducted to analyse the effects.” He adds that people living in households where smoke is produced by burning of fuel are at risk of eye infections and allergic conjunctivitis in this season.

La Nina effect

Meanwhile, cold weather conditions continued to hit northern India with hilly states like Uttarakhand and Himachal Pradesh experiencing heavy snowfall. J R Kulkarni, senior scientist at the Indian Institute of Tropical Metereology at Pune, maintains this is usual for this time of the month. D S Pai, director of the long-range forecasting division, IMD Pune, says that people are feeling colder because of dip in maximum or day temperature. He adds that La Nina, a weather phenomenon generally associated with favourable monsoons and WHICH occurs when surface temperatures are cooler than normal in the western Pacific and warmer than normal in the eastern Pacific, might have been one of the factors behind this severe cold. “Weather is complicated, and La Nina is not the most important factor to influence temperature, but our analyses have shown that it can impact mean temperature.”

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