Why is humidity often highest around sunrise?
After a night without the input of any solar energy, it is often coolest at sunrise. Relative humidity — a percentage that measures how close the air is to being saturated — increases as the air temperature drops closer to the dew point temperature. Relative humidity tends to be highest during the coolest part of the day and reaches its lowest value during the heat of the day, when the difference between air temperature and dew point is greatest. Learn more about humidity on this USA TODAY resource page. (Answered by meteorologist Bob Swanson, USA TODAY’s assistant weather editor, Nov.