Tell me how CFCs that are heavier than air can reach the upper atmosphere?
CFC atoms affix themsleves to the heated air coming out of the capitol building and rise to the top with the hot air.
“Tell me how CFCs that are heavier than air can reach the upper atmosphere?”
There’s enough random motion among the molecules in the atmosphere that even heavier molecules can end up distributed at essentially all altitudes. Heck, even macroscopic particles - orders of magnitude heavier - can end up at high altitudes in dust storms and the like.
The migration of CFC’s to the upper atmosphere is exacerbated by their relative chemical inertness (at least until they encounter high-energy UV radiation up there), and is well-established both theoretically and experimentally.