Gujarat: Heat islands in cities affecting rain pattern, reveals study

VADODARA: Ever wondered why it's pouring cats and dogs in Ahmedabad's Satellite area, but the sun is shining bright a few kms away on Ashram Road at the same time? Or, Vadodara's posh Alkapuri is pounded while the airport runway is dry?

Global warming impact is obvious, but a study done by M S University researchers has revealed that even local climatic conditions and micro urban heat islands are impacting rainfall patterns in Vadodara, Ahmedabad and Surat.

Micro urban heat islands are usually urban hotspots that are poorly vegetated, barren lands, huge parking lots, dumping sites that generate heat and long stretches of concrete structures or asphalt roads.

The study explains that significant difference in temperature of different areas, one of the fundamental reasons for rain along with obstruction to clouds, is the reason for this phenomenon.

"In areas with higher temperatures, the evaporation loss is more from all surfaces, thus reducing rainfall," said Dr Sanskriti Mujumdar, associate professor at civil engineering department of Faculty of Technology and Engineering (FTE).

For instance, on a day in April this year when the dumping site at Pirana in Ahmedabad clocked 47.58 degrees Celsius, the temperature at Sabarmati riverfront was 31.37 degrees - a difference of 16.21 degrees.

"In urban areas, warm front and cold front get created because of the difference in temperatures of different areas. It is a natural phenomenon that air which is warmer compared to the surrounding air, moves upward," said Mujumdar.

During monsoon, when the moisture-laden air passes through the greener patches or cooler areas of the city, there is condensation because of temperature difference which leads to heavy rain.

The study involving PhD scholars Chirayu Pandit and Nirav Agarwal and research associate Akash Patel revealed that in each of the three cities of Gujarat, the temperature difference is in the range of at least 10 to 12 degrees.

Within the limits of Vadodara Municipal Corporation (VMC), the west zone, which has more green cover, records more rain compared to east, north and south zones.