the.com/cloud nine

means A state of blissful, floating-on-air happiness — so euphoric you're practically off the ground.

from The real origin is murky, which hasn't stopped people from guessing. One popular story ties it to an old U.S. Weather Bureau cloud classification where cumulonimbus (the big, piled-high, dreamy-looking ones) was numbered nine — but there's no solid evidence this classification ever existed as described, so treat it as folklore. The phrase likely grew simply from the image of clouds as high, soft, and far from earthly troubles, with 'nine' chosen because it sounded like the top of some ascending scale. It surfaced in American slang by the mid-20th century and stuck because the image does all the work.