Learn Hardcore German: Im Bus ist es so warm, dass ich den Pullover ausziehe und trotzdem schwitze. - On the bus it is so warm that I take off the sweater and still sweat.

The base preposition is in (“in / inside”).
Bus is masculine: der Bus in the nominative.
With in meaning location (“in the bus” as a place you are in, not a direction you’re moving toward), German uses the dative case: in dem Bus.
In everyday German, in dem almost always contracts to im:
- in dem Bus → im Bus

You would only write in dem Bus if you really want to emphasize dem for some special contrast, which is rare in normal speech/writing.

Why does the sentence start with Im Bus ist es so warm instead of Es ist so warm im Bus?

Both Im Bus ist es so warm and Es ist so warm im Bus are grammatically correct. The difference is emphasis and style.

German main clauses follow a verb-second (V2) rule. One “slot” comes before the finite verb; almost anything can stand there:

Im Bus ist es so warm … → The place (in the bus) is emphasized.
Es ist so warm im Bus … → More neutral; typical translation of “It is so warm in the bus.”

By putting Im Bus first, the sentence highlights the setting (the bus) as the topic of the comment that follows. This is very common in German.

What is the function of es in ist es so warm? Is it like English “it”?

Yes. Here es is a dummy (impersonal) subject, like English “it” in “It is warm”.

German often needs a subject in structures like Es ist warm, Es regnet, etc. There is no specific “thing” that is warm; it’s just the general environment.

Other options that are also common:

Es ist so warm im Bus. – “It is so warm in the bus.” (impersonal)
Mir ist so warm im Bus. – “I feel so warm in the bus.” (focus on your personal feeling)

In the original sentence, es refers vaguely to “the situation/temperature in the bus,” not to a concrete object.

How does the so … dass structure work in so warm, dass ich den Pullover ausziehe?

So … dass … is a standard way to express “so … that …” (result):

Es ist so warm, dass ich den Pullover ausziehe.
→ “It is so warm that I take off my sweater.”

Structure:

so + adjective/adverb in the main clause:
- so warm, so laut, so schnell
dass introduces a result clause (a subordinate clause):
- …, dass ich gehen muss. – “… that I have to go.”

Points to note:

dass (with double s) is a conjunction (“that”), not the article/pronoun das.
A comma is required before dass.
The verb in the dass-clause goes to the end:
- dass ich den Pullover ausziehe (not dass ich ziehe den Pullover aus).

Why is the verb at the end in dass ich den Pullover ausziehe?

Because dass introduces a subordinate clause, and in German subordinate clauses, the finite verb goes to the end of the clause.

Pattern:

Main clause (V2):
- Ich ziehe den Pullover aus. – finite verb ziehe in second position.
Subordinate clause (verb-final):
- …, dass ich den Pullover ausziehe. – finite verb ausziehe at the end.

This is a general rule:

…, weil ich müde bin.
…, obwohl er kein Geld hat.
…, dass ich den Pullover ausziehe.

Why is it den Pullover and not der Pullover?

Pullover is a masculine noun:

Nominative singular: der Pullover
Accusative singular: den Pullover

In ich den Pullover ausziehe, den Pullover is the direct object (“I take off the sweater”), so it must be in the accusative case.

Case breakdown:

Nominative (subject):
- Der Pullover ist neu. – “The sweater is new.”
Accusative (direct object):
- Ich ziehe den Pullover aus. – “I take (off) the sweater.”

Why is it ausziehe instead of ziehe aus, and what’s going on with this verb?

The base verb is ausziehen (separable verb).

In a main clause, separable verbs split:

Ich ziehe den Pullover aus.
- ziehe (finite verb) in position 2
- aus (separable prefix) at the end

In a subordinate clause (like after dass), the verb appears as one unit at the end:

…, dass ich den Pullover ausziehe.

So:

main clause: ziehe … aus
dass-clause: ausziehe

Same pattern with other separable verbs:

Ich stehe früh auf. → …, dass ich früh aufstehe.
Ich rufe dich an. → …, dass ich dich anrufe.

Why isn’t ich repeated before schwitze? Why not dass ich den Pullover ausziehe und ich trotzdem schwitze?

You can say … und ich trotzdem schwitze, but it’s not necessary here because the subject ich is shared.

In dass ich den Pullover ausziehe und trotzdem schwitze:

ich is the subject of both verbs (ausziehe and schwitze).
German allows you to omit the repeated subject in a coordinated verb phrase if it’s the same:

Examples:

dass ich ins Kino gehe und Popcorn esse
(short for dass ich ins Kino gehe und ich Popcorn esse)
dass ich den Pullover ausziehe und trotzdem schwitze

Adding ich before schwitze sounds a bit heavier and more emphatic:
…, dass ich den Pullover ausziehe und ich trotzdem schwitze.
This might be used if you want to stress “even I still sweat” or clearly segment the parts, but the shorter version is more natural.

What does trotzdem mean here, and why is the word order trotzdem schwitze?

trotzdem is an adverb meaning “nevertheless / anyway / even so”.

In a main clause, adverbs like trotzdem can be placed in first position, but German still keeps the verb in second position (V2):

Trotzdem schwitze ich. – “Nevertheless I am sweating.”

In the sentence:

…, dass ich den Pullover ausziehe und trotzdem schwitze.

Inside the dass-clause, the part ausziehe und trotzdem schwitze is treated as a joint verb bracket at the end:

dass – ich – den Pullover – ausziehe und trotzdem schwitze

Within that joined structure, schwitze is still the last verb element; trotzdem comes right before it as its adverb.

Meaning-wise, trotzdem expresses that even though the sweater is taken off, the result (sweating) still happens.

Could I use obwohl instead of trotzdem? For example: Obwohl ich den Pullover ausziehe, schwitze ich.

Yes. obwohl and trotzdem both express contrast, but they work differently:

obwohl = subordinating conjunction (“although”)
trotzdem = adverb (“nevertheless”)

Two ways to express the idea:

With obwohl (subordinate clause):
- Obwohl ich den Pullover ausziehe, schwitze ich.
- Verb in the obwohl-clause goes to the end (ausziehe).
With trotzdem (adverb in a main clause):
- Ich ziehe den Pullover aus, trotzdem schwitze ich.
- trotzdem is in the main clause; verb stays second.

Semantically, they’re very close:

obwohl … = “although …”
trotzdem … = “even so / nevertheless …”

The original sentence chooses dass … und trotzdem schwitze, combining a result clause (dass) with an adverb of contrast (trotzdem).

Why is the present tense used (ausziehe, schwitze) instead of some progressive form?

German doesn’t have a grammatical progressive tense like English “I am sweating”.

The simple present covers:

general present:
- Ich arbeite jeden Tag. – “I work every day.”
actions happening right now:
- Ich schwitze. – “I am sweating.”

So in:

…, dass ich den Pullover ausziehe und trotzdem schwitze.

both ausziehe and schwitze naturally describe what is happening at that moment, even though in English you’d likely say:

“that I’m taking off my sweater and still sweating.”

Why is there a comma before dass, but not before und trotzdem?

Commas:

Before dass:
- dass introduces a subordinate clause, and German always requires a comma before such clauses:
  - …, dass ich den Pullover ausziehe …
Before und trotzdem:
Inside the dass-clause we have a simple coordination of verbs (“take off and sweat” with the same subject):
- dass ich den Pullover ausziehe und trotzdem schwitze
There is no new independent clause here; it’s just one subordinate clause with two coordinated predicates.
Therefore, no comma is needed before und.

If you separated them into two independent main clauses, then a comma could appear:

Ich ziehe den Pullover aus, und trotzdem schwitze ich.
(two main clauses linked by und)