Astrophysicistsworking withground based detectorsat the South Poleandballoon borne instrumentsareclosing in on such structures, and mayreporttheirfindingssoon.
Ms. Resler grew up in the more urban milieu of Seattle but had a backyard that she describes as the perfect staging ground for a neighborhood water balloon fight.
Unstable means that if an imaginary balloon filled with air from near the ground were to be lifted upward, colliding with some weather feature such as a cold front, the "balloon" would become warmer than the surrounding air at that level.