Bit of a science lesson for you today, chaps.

Chennai is a coastal city in the tropics which means that most of the time it feels like your whole body is wading through pea soup and you have to push the air out of the way. The air is literally saturated with water and right now it is worse than ever. Today it was 32°C outside which might seem quite nice but the air humidity was 94%. Humidity is a measure of how much moisture is in a body of air and when it gets to 100% it means the air is completely saturated and can’t hold any more water – your sweat will simply pool on your skin as it has no where to go.

The human body keeps cool by sweating and then evaporating the moisture from your skin which works pretty well if it’s 32°C outside and the air is fairly dry, say 60% humidity or less. Above 60% humidity is where the problems start because less sweat is able to evaporate in to the already saturated air so 32°C with 60% humidity actually feels like 37°C because you’re not able to evaporate enough sweat to cool down.

As I said earlier, today in Chennai it was 32°C with 94% humidity which (apart from feeling like wading through water) makes it feel like a rather balmy 51°C. The American Government weather site has some reassuring information for temperatures and humidity like this: Extreme risk of death, do not go outside.

Useful to know!