Atmospheric Pressure

I’ve heard about atmospheric pressure, but honestly, it’s not a thing I get - only that it’s something people measure, and when it’s low, I hear we might get wet! I guess they never taught me it in school. In fact, I googled it just now. It said we’re living in the bottom of a pool, just one with air – not water – overhead! I really like that nifty metaphor, but how warm air that rises makes it low I can’t quite comprehend, and I get more confused when reading how it makes wind blow! My brain’s now fried. I just can’t get the gist of it! And that’s why I’m no scientist! Sept. 2, 2017 for Shadow Hamilton's Atmospheric Pressure Poetry Contest