Before the summer rainstorm, the weather was sultry and dark clouds rolled. Try to analyze and explain why this phenomenon occurs.

It's the pressure. When the air pressure adapted by the human body suddenly becomes lower, the pressure in the body will be greater than the external pressure ~ the heat and water in the body will be lost in large quantities ~ it will be released from the body surface in the form of radiant heat and sweat ~ so it feels sultry.

Dark clouds roll because clouds are mixed together ~ because the density is different ~ light is reflected or refracted ~ so they are dark clouds ~