This is NOT an atomic bomb cloud or mushroom cloud. This is far from a cloud. It’s a weather phenomenon called a microburst or downburst. It’s a downward wind (science term downdraft) that brings heavy rain and damaging winds in thunderstorms. Microbursts for when a storm’s downdraft is so strong that it looks like the clouds are coming down. What stuff that looks like clouds touching the ground, that’s actually very heavy rain. It flattens out at the bottom because the wind shifts parallel to the ground. That’s when the winds shift from vertical to horizontal and do a lot of damage.