Air always seems cleaner after a rainfall. That’s because raindrops condense around all the gunk in the sky. That’s stuff like dust, pollen, and pollution.
As rain falls, it wraps around sulfur particles and takes them down too. The scrubbed air naturally smells cleaner.
Rain is also a mild, natural acid. It can eat away at solid rock over time. But many of the chemicals humans have put in the air make rain way too acidic. Acid rain is bad for plants, animals, and people. Today, it’s just one of many problems precipitation can bring.