Learn Dutch: Waar zijn de wolken vandaag? - Where are the clouds today?

The singular word is wolk. To make it plural, we just add the regular -en ending. Because wolk ends in two consonants (l and k), there is no need to double any letters or change the vowel. It simply becomes wolken.

Is cloud a de word or a het word in Dutch?

The singular is de wolk. However, in this sentence, it wouldn't actually matter! In Dutch, all plural nouns always use de as their article, even if their singular form is a het word. Since wolken is plural, it has to be de wolken.

Why is the verb zijn used here instead of is?

Zijn is the dictionary form of the verb "to be", but it is also the specific form used for all plural subjects in the present tense (we are, you all are, they are). Because our subject de wolken (the clouds) is plural, we must use zijn.

Why does the verb zijn come right after Waar?