First appeared in Future. Reprinted (once in a genre retrospective) by Groff Conklin, Robert Silverberg, Terry Carr, and John Gregory Betancourt.
The narrator and Ed, meteorologists, head out to Wyoming to check out a meteor and unusual storms, one after another. The researchers discover glass globes instead of a meteor and strange, vegetative air you'd smell on a warm day... except it was cold. They spy something glassy a ways away.
*Spoiler* The meteors are glass bubbles, leaking alien air. Aliens are converting our atmosphere into something more comfortable for them.
Funky fun speculation: The tale proposes water as a source of life, rather than an excellent solvent and transport medium. Earth's air and this alien air duke it out for supremacy. Perhaps this is the source of storms, epic battles waged without our knowing. The science is a little wonky although maybe less so when it was published.
The story ends on "That's what I think." which is either a blemished ending or calls into question what's been said, which makes sense for the odd science hypotheses, but then it's hard to tell what occurred otherwise. If there's an unreliable narrator, some alternate theory (theories) should be supplied.