Bangalore blows hot and cold this winter

 An ongoing study by the Department of Environmental Science, Bangalore University, has come out with some very interesting findings on the climate changes in the City.

The weather monitoring station at the university has been recording temperature, relative humidity, wind speeds and various other weather parameters on a daily basis since 2009 and the exercise will continue till the end of 2012.

The readings of the Meteorological department over the past two weeks (November 12 - November 25) have shown quite a change in the daily average temperatures.

For example, November 17 saw a maximum temperature of 28.1 degree Celsius and a minimum of 14.1 degree Celsius. A maximum temperature of 29.1 degree Celsius and a minimum temperature of 13.1 degree Celsius were recorded on November 19.

The readings were a lot different on November 21 with maximum and minimum temperatures being 30.8 degree Celsius and 20.2 degree Celsius respectively.

Director, Meteorological Department, B Puttanna said such fluctuations were nothing out of the ordinary and were part of a regular pattern of weather change.

Some findings

In 2010, when the world and India (with an average of 24.64 degrees Celsius) experienced their hottest temperatures, Bangalore recorded a temperature of 29 degree Celsius. The relative humidity averaged 95 percent in 2009, but this figure fell to 20 per cent in 2012 (November).

Wind speeds in 2011 averaged five miles per hour (mph), whereas in 2012 it was nine mph. The higher wind speeds result in the body losing moisture, thereby pushing up the temperature. The study also reveals that the release of anthropogenic gases in the City has increased. In 2012 (November), the amount of nitrogen dioxide, a major greenhouse gas, stands at 16.8 microgram per cubic metre.

This was higher than in 2011, when it was 15.8 microgram per cubic metre. Other gases like nitrous oxide and nitrous dioxide have also seen an increase, according to the study. The unending problem of garbage has also contributed to the growing temperature.

“Gaseous emissions of methane and hydrogen sulphide from the garbage also causes increase in temperatures,” according to Dr N Nandini, Associate Professor, Department of Environmental Science, Bangalore University.

The vanishing lakes in the City is another important factor responsible for the rise in temperature. There were 2,789 lakes before 1920 and by 1985, this number came down to 34. Presently, there are around 110 lakes in the City, according to Nandini. “The vanishing water bodies cause a reduction of humidity in the atmosphere and make the air dry,” she said.

Other factors are deforestation and expansion of the City, negative attitudes of people towards their ecology and the floating population, who by their various activities cause an increase in the carbon footprint of the City. Regional pollution like release of greenhouse gases from vehicles and industries can cause the sudden warming and cooling of temperatures in a particular region, according to her.

Any real change in the weather and climatic pattern requires a study and monitoring over a longer period of time, according to Puttanna. “A minimum period of 30 years is needed to gauge the changes in climate and weather,” he said.  

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