[Mengkudulangsat]

Isn't SF6 very dense?

Why would its greenhouse warming potential matter if it's never going high up into the atmosphere in the first place?

[pfdietz]

Gases in the atmosphere separate by molecular weight only at very high altitude, above the "homopause". This is from 80 to 120 km. Below that altitude, turbulence remixes gases faster than they can separate.

[Metacelsus]

It will mix throughout the troposphere like any other gas.