How did sauna days come into being?

"Sauna day" generally refers to the weather where the temperature is above 32℃ and the lowest relative humidity reaches 80%. Chongqing has always ranked first among the four major stoves in the mainland, and the high temperature of 38 degrees will last for more than two weeks every summer. The whole mountain city is like being in a huge steamer. It's humid and sultry, and the sauna is free all day. The relative humidity is 100%. I dare not wear clothes at home in summer. It is not only hot in summer, but also cold in winter. In recent years, there are more and more "sauna days" in summer. This is because of global warming-the greenhouse effect. This phenomenon is becoming more and more obvious. Many factors, such as deforestation, animal culling and environmental pollution, are the direct killers of accelerating global warming.