The National takes on the heat (index)

Yesterday was the first day of summer, and the launch of The National's season-long weather experiment.

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ABU DHABI // How hot is too hot? It's a question that takes on a new meaning each summer as the mercury rises from the beginning of June and throughout July and August. Official weather forecasts use sophisticated technology, operated under internationally approved guidelines, to measure air temperature readings. But while these can give consistent and scientifically-precise data, they might not always reflect the feeling on the street. Factors such as the urban environment, with tall buildings trapping the heat, influence perceptions, making it feel a few degrees hotter than it actually is.

Yesterday was the first day of summer and The National began conducting its own experiment. We will take temperature readings every day throughout the season to see if our recordings match official figures. Experts agree that even an objective measurement such as air temperature is not set in stone. Where the temperature was measured can make a significant difference, said Dr George Odhiambo, assistant professor of geography and specialist in hydro-meteorology at UAE University.

"You will find that someone on a city street might experience temperatures higher than those recorded at weather stations," he said. Meteorologists rely on data from weather stations, which are usually located at airports or in open areas away from large cities. "Weather stations are located in open areas to prevent tall buildings interfering with the readings, for example by obstructing air flow," he said.

But most of the population lives in cities, where a range of factors can affect readings, he said. "Concrete and road tarmac absorbs heat and retains it for a long time," he said. As buildings and roads emit the trapped heat, a city would be hotter than its natural surroundings. This is due to a phenomenon known to city planners as the "urban heat island effect", which can push temperatures up by an average two to three degrees.

Dr Waleed Hamza, head of biology at UAE University, said the approved methodology for measuring air temperature required that thermometers be kept in the shade. But for those out in the sun, air temperatures measured in the shade do not tell the whole story. "If you take a thermometer and go out in the sun, you will find temperatures of 57°C," said Dr Odhiambo. Humidity also plays a significant role, said Ahmed Sajwani, a weather blogger. "Even if it is only 40°C outside, it can feel like 50 because of the humidity," said Mr Sajwani, who is taking an online certificate in meteorology at Pennsylvania State University in the United States, and has developed an application that enables iPhone users to get local weather updates.

Long-suffering residents know all too well the ferocity of the summer sun. For Yasmin Wadhai, a personal trainer and long-term Abu Dhabi resident, summer arrived in mid-May. That was when she had to reschedule the time of her five-day-a-week jogging and cycling exercise routine. "It is not possible to train between 7am and 6pm now," she said. "It is too hot - you can get sun stroke." For Ms Wadhai, who recently completed the Abu Dhabi International Triathlon, air temperatures reported by meteorologists only tell half the story. "I think they measure the temperature in the shade," she said. "But I don't think this tells you the real deal out there."