Relative humidity measures how much moisture is in the air compared to how much it could hold at a given temperature. It is simply the dew point temperature divided by the air temperature, times 100.

This episode is brought to you by the Music for Scientists album! Have you ever wondered why 75% humidity in the summer feels ...

The humidity plays a big part in making you feel sluggish and tired. (Getty Images) If you’ve been feeling strangely sluggish during the UK’s fourth heatwave of the year, you’re not imagining it. It’s ...