Science features

Courtesy of the Royal Meteorological Society

With snow on the ground and a chill in the air, it certainly seemed an odd day to investigate something known as the Urban Heat Island (UHI) effect.

School pupils took part in the experiment

But on 6 March, between 6am and 8am, more than a thousand people, including weather enthusiasts and schoolchildren, braved the cold to record the air temperature which they reported by text to the Royal Meteorological Society (RMS).

From those 1,000+ readings, RMS scientists have built up the first ever map of Greater Manchester coloured according to the temperature readings.

Warmer

What it revealed were a number of hot spots in Manchester and Stockport, with the leafy suburbs of South Manchester staying ‘greener’ and cooler. So was it a success? We asked Dr Sylvia Knight of the RMS.

"Definitely," she said. "And we will be repeating it in other cities across the country."

The theory behind the UHI effect states that built-up areas like city centre are up to 10C warmer than outlying rural areas because of the taller buildings, lack of green space and the heat absorbing properties of materials such as concrete and tarmac.

Profile of a typical Urban Heat Island

The idea behind the experiment is, that by gathering accurate data on the temperature of cities, new buildings can be designed to stay cooler for longer.

Added Dr Knight: "Obviously, it's always better if you have more data and there’s a lot of variation in the accuracy of people’s thermometers. But this was still a worthwhile experiment."

Design

Dr Claire Smith, an expert on Climate Change Adaptation at the University of Manchester said the information gathered would be useful in the future.

Adding: "A building in the city centre is more likely to experience overheating. This means that people who live there are more likely to install air conditioning, which not only has an impact on energy use but also results in more heat being pumped out into the atmosphere."

However, Dr Smith did admit that conditions on the day were not ideal. "The UHI effect is best observed a few hours before sunrise on a clear night,” she said.

"However, on the morning of the experiment, a lot of cloud built up which reduced the heat gradient from the ground to the sky. So there was less of a contrast between rural and urban areas than we would have expected."