Learn Hardcore German: Wenn es draußen laut ist, schließen wir das Fenster wieder. - When it is loud outside, we close the window again.

Main clause: Es ist draußen laut. (verb in 2nd position)
Subordinate clause: …wenn es draußen laut ist. (same words, but ist moves to the end)

So wenn es draußen laut ist is just the “dependent” version of es ist draußen laut.

What exactly does wenn mean here, and how is it different from wann, als, and falls?

In this sentence wenn means "whenever / when(ever)" in a general, repeated sense, and also works like "if" in English.

wenn – “when(ever)” / “if” for:
- repeated events: Wenn es laut ist, schließen wir… (Whenever it’s loud…)
- general conditions: Wenn es regnet, bleibe ich zu Hause.
wann – only for questions about time:
- Wann kommst du? (When are you coming?)
- Ich weiß nicht, wann er kommt.
als – “when” for a single event in the past:
- Als ich klein war, wohnte ich in Berlin.
falls – “in case / if” (more hypothetical / tentative):
- Falls es laut ist, schließen wir das Fenster.

Here wann or als would be wrong; falls would slightly shift the meaning to “in case it’s loud”.

Why do we need es in wenn es draußen laut ist? Could you say wenn draußen laut ist?

You need es because German almost always requires an explicit subject, even when English uses no subject or a vague “it”.

Here es is a dummy subject (like “it” in It is loud outside). You cannot say *wenn draußen laut ist; that sounds ungrammatical.

The “normal” main clause would be Es ist draußen laut. The es carries almost no meaning, but it’s required for the sentence structure.

What does draußen mean exactly, and how is it different from außen?

draußen means “outside, outdoors” – usually outside the building or room you’re in.

außen means “on the outside / on the outer side”, often referring to the outer surface of something:

Die Tür ist außen rot. (The door is red on the outside.)
von außen = from the outside (surface/side)

In this sentence you’re talking about noise from outside (outdoors), so draußen is the correct word.

Why is the main-clause part schließen wir das Fenster wieder instead of wir schließen das Fenster wieder?

German main clauses have the verb in 2nd position. When the sentence starts with something other than the subject (here, the whole wenn-clause), that whole chunk counts as position 1 of the main clause, so the finite verb must come next:

Neutral order: Wir schließen das Fenster wieder, wenn es draußen laut ist.
With the wenn-clause first: Wenn es draußen laut ist, (1st position) → schließen (2nd position = verb) wir das Fenster wieder.

So schließen wir… is just the normal verb-second rule at work; both versions are correct.

Why is it das Fenster and not something like dem Fenster or den Fenster?

Fenster is a neuter noun in German.

Nominative singular: das Fenster
Accusative singular: das Fenster
Dative singular: dem Fenster
Plural (nom./acc.): die Fenster

In this sentence, das Fenster is the direct object of schließen (we close the window), so it must be in the accusative. For neuter nouns, nominative and accusative are both das, so you get das Fenster.

What is the function of wieder in schließen wir das Fenster wieder, and why is it at the end?

wieder means “again / back (to the previous state)”. So das Fenster wieder schließen = “to close the window again / to close it back”.

Position-wise, wieder is an adverb, and adverbs often appear towards the end of the clause, after the object:

Wir schließen das Fenster wieder. (most neutral)
Wir schließen wieder das Fenster. (more emphasis on again and on the window in contrast to something else)

In your sentence, …das Fenster wieder is the most natural and common order.

Can I also say Wir schließen das Fenster wieder, wenn es draußen laut ist? Does it change the meaning?

Yes, that sentence is completely correct, and the meaning is basically the same.

Wenn es draußen laut ist, schließen wir das Fenster wieder.
- Slight emphasis on the condition (“whenever it’s loud outside…”).
Wir schließen das Fenster wieder, wenn es draußen laut ist.
- Slight emphasis on what we do (“we close the window again when it’s loud outside”).

This is mostly a matter of focus and style, not of grammar or core meaning.

Can I leave out wir, like you can drop subject pronouns in Spanish or Italian?

No. In standard German you cannot normally drop the subject pronoun.

Correct: Wir schließen das Fenster wieder.
Incorrect as a normal statement: *Schließen das Fenster wieder.

Without wir, Schließen das Fenster wieder. would be understood as an imperative (Schließen Sie / wir das Fenster wieder!) or just as wrong, depending on context. German is not a “null-subject” language in the way Spanish or Italian are.

How do you pronounce draußen, and what is that ß letter?

ß is called “Eszett” or “scharfes S” and is pronounced like a double s (ss) in English “hiss”.

draußen is pronounced roughly like "DROW-sen":
- dra(u) = like the ow in now
- ß = s as in see
- final -en = about like -en in taken (unstressed)

In Switzerland you’ll often see draussen instead of draußen; it’s pronounced the same.

Why is the present tense used (ist, schließen) even though English would probably say “we will close the window again”?

German uses the present tense much more broadly than English, including for future events when the context makes the time clear.

Wenn es draußen laut ist, schließen wir das Fenster wieder.
- Can mean: “When(ever) it’s loud outside, we close the window again” or
- “When it’s loud outside, we’ll close the window again.”

You could say werden wir das Fenster wieder schließen, but here that sounds heavy and is usually unnecessary. The plain present is the natural choice.

Could I say wenn es laut draußen ist or wenn es laut ist draußen instead of wenn es draußen laut ist?

All these orders are grammatically possible, but they don’t sound equally natural:

Most neutral / typical: wenn es draußen laut ist
wenn es laut draußen ist – possible, but slightly marked; it puts a bit more focus on laut and on the contrast “loud outside (not somewhere else).”
wenn es laut ist draußen – sounds more spoken/colloquial and a bit disjointed.

For learners, wenn es draußen laut ist is the best and most natural word order to stick with.