Learn Hardcore Korean: haneure gureumi tteo isseoyo. - There are clouds floating in the sky.

In Korean, 에 marks a static location (“in/at”). Here, the clouds simply “exist” or “float” in the sky, so we use 하늘에 (“in the sky”). On the other hand, 에서 indicates where an action takes place (“from/at doing something”), e.g. 하늘에서 비가 내려요 (“Rain falls from the sky”). Since floating is treated as a state rather than an action “performed” in the sky, 에 is correct.

Why does 구름 take the subject particle 이 here?

The phrase 구름이 떠 있어요 is a full sentence describing “what” is floating. 이/가 marks the grammatical subject. Even though 하늘에 gives the location, 구름이 tells us that the clouds are the ones doing (or rather, being in) that state—so you need 이 to show that 구름 is the subject.

What exactly does 떠 있어요 mean? Is it like “float” in English?

떠 있어요 comes from the verb stem 뜨다 (“to float”) combined with the auxiliary 있다 (“to be”). Together they form 뜨 + 어 있다 → 떠 있다, which literally means “to be floating” (i.e. remain in a floating state). The ending -어요 simply makes it polite: “(They) are floating.”

Why can’t I just say 구름이 떠요?

구름이 떠요 (“the clouds float”) would sound like you’re describing a habitual or momentary action—like “the clouds float (around).” But in Korean, for ongoing states or conditions resulting from an action, you use -어/아 있다. So to express “the clouds are in the state of floating (right now),” you need 떠 있어요.

How is -어 있다 different from the progressive -고 있다?

-고 있다 describes an action in progress (e.g. 구름이 떠 있고 있어요 would be overly wordy and isn’t natural).
-어/아 있다 expresses a resulting state that continues after an action has happened. With 떠 있다, the act of “floating” has occurred and the state of floating persists. That’s why we say 구름이 떠 있어요, not 구름이 뜨고 있어요.

Could I say 하늘에 구름이 있어요 instead?

Yes, grammatically it’s fine: 하늘에 구름이 있어요 means “There are clouds in the sky.” But this just states existence. 떠 있어요 adds the nuance that the clouds are floating—moving or drifting—rather than just “present.”

Can I swap the particles and say 구름은 하늘에 떠 있어요?

Absolutely. Switching to 은 gives a slight topical emphasis on 구름 (“As for the clouds, they’re floating in the sky”). It doesn’t change the basic meaning, but it shifts the focus to “the clouds” as the topic.

How do I pronounce 떠 있어요 in natural speech? Any contractions?

You’ll often hear it spoken as 떠있어요 [tteo-iss-eo-yo], with the two words linked. There isn’t a standard contraction like 떠써요—you just blend the vowel-ending stem 떠 with 있어요, dropping any pause: 떠있어요.

What about formality? Can I use 떠 있습니다?

Yes. In very formal or written contexts, you can use the declarative formal ending -습니다: 하늘에 구름이 떠 있습니다. In everyday polite speech, though, 떠 있어요 is more common.