This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated. First, let’s define relative humidity.

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.

The ability of air to hold water vapor decreases as temperature decreases, halving for about every 20 degrees of temperature decline. Dew point is the temperature at which air is saturated with water ...

Some hot days feel even worse thanks to high humidity, trapped heat and dew points. Cities are especially vulnerable. By Nazaneen Ghaffar Nazaneen Ghaffar is a reporter on The Times’s weather team. It ...

Industry leaders realized hundreds of years ago that their processes and machines operate best when the indoor relative humidity is maintained at an optimum level for their process. They found it was ...

Across much of the world, hotter days are no longer arriving alone. The air itself is changing, sometimes turning from dry oven to steam bath, other times drying out even as thermometers climb. As ...