Cloud – la nube
(Pronounced noo-bay)
To remember that cloud is pronounced noo-bay (nube) in Spanish, use the following mnemonic:
A huge cloud came over and there was a violent storm – then they saw that a new bay (nube) had formed where the shore had been washed away.

Nube is feminine, so it's la nube. Imagine a cloud that is shaped like a lady:

Examples of nube (cloud) in a sentence
Hay una nube grande en el cielo hoy.
(There is a big cloud in the sky today.)
La nube parece un conejo esponjoso.
(The cloud looks like a fluffy rabbit.)
Las nubes oscuras anuncian una tormenta.
(The dark clouds announce a storm.)