Mammatus clouds put on stunning display across eastern Iowa following hail storms

CEDAR RAPIDS, Iowa (Iowa's News Now) — WHAT ARE THOSE? The bulbous clouds in the sky Sunday evening stunned and perplexed people across eastern Iowa.

These are mammatus clouds, they are typically seen before, during or after thunderstorms. They form due to cold air sinking down and forming these pockets in the clouds. They are most commonly associated with hail storms.