Washington Post – Humidity has increased 5 to 10 percent since 1970, turning hot summer days even more unbearable: “It’s no secret the world is warming, but thanks in part to climate change, humidity is also beginning to surge. Here in Washington, that means the punishing combination of heat and humidity is becoming more oppressive. We reviewed data from four locations in the District and broader region. Through this, we calculated specific humidity, which is the mass of water in a volume of air. (It’s a much better indicator of how oppressive it feels than the relative humidity, to which we are accustomed.) To calculate these trends in humidity, it took a lot of number-crunching — involving close to 2 million data points — with observations stretching back as far as the 1930s. In the end, we found that the District is, on average, a little more than 5 percent more humid than it was in 1970, and slightly more than 10 percent juicier than in 1950. This is important because humidity affects how we feel. Take Wednesday, for instance. The average high for this time of year at Dulles Airport is 86 degrees. With 1970s humidity, a typical summertime afternoon would produce a heat index (a measure of how hot it feels) of 89 degrees. Now, when you factor in a higher humidity, it feels closer to 91 or 92 — and that’s at the same 86 degrees…”