Sarah writes about 'Feeling the heat'

The highest ever recorded in the
eastern hemisphere was at the
Kuwaiti town of Mitribah in July
when the temperature reached 54ºC.

On a very hot day in late July, the temperature in the Kuwaiti town of Mitribah reached 54ºC, the highest ever recorded in the eastern hemisphere. Across the Persian Gulf, Fujairah in the United Arab Emirates was experiencing what looked like a relatively cool 36ºC. Thanks to blistering humidity, though, the “heat index” for Fujairah registered 60ºC.

Heat index might not be a well-known term, but it describes how the weather feels to us rather than how it feels to the mercury. Designed back in 1979, it incorporates the effect of relative humidity, and assumes we’re wearing light clothing. At 50 per cent humidity, 30ºC feels like 31ºC; at 90 per cent it feels like 40ºC. The more moisture in the air, the hotter it seems to us and the higher the heat index.

And there’s an extra factor affecting our perception. For every rise of 1ºC, air can hold 7 per cent more moisture. So the amount of moisture in the air is potentially much higher at 35ºC than, say, 25ºC. This makes 90 per cent humidity much harder to bear at 35ºC than at lower temperatur

Read the Inside Story by a research fellow at the ARC Centre of Excellence for Climate System Science, at the Climate Change Research Centre, at the University of New South Wales, Sarah Perkins-Kirkpatrick - “Feeling the heat.”