In a mnemonic purpose for those concerned, a parallel between the french "nimbes" and the russian "небе" is interesting. Apparently, they both come from the Proto-Indo-European nébʰos.
Ай на не-е-бе тучи, а тучи, а тучи, как лю-у-уди они-и-и один-о-оки. Как жест-о-око. It's Russian song. Иванушки International
English speakers often refer to "dark" clouds for storm or rain clouds, so I'm submitting that as an alternative. And if you were asking about Russian then yes - I've seen an explanation on another exercise