Cumulonimbal is not a word, but the word cumulonimbi looks like that and that means; An extremely dense, vertically developed cumulus with a relatively hazy outline and a glaciated top extending to great heights, usually producing heavy rains, thunderstorms, or hailstorms. Hope that helped!
Now in case you were wondering. . . . . .
Cumulonimbal is not a word, but the word cumulonimbi looks like that and that means; An extremely dense, vertically developed cumulus with a relatively hazy outline and a glaciated top extending to great heights, usually producing heavy rains, thunderstorms, or hailstorms. Hope that helped!