Learn Hardcore Swedish: På kvällen är himlen mörk men vacker. - In the evening the sky is dark but beautiful.

In this expression, på is best translated as “in” or “at”, but it’s really just the standard preposition used with many time expressions in Swedish.

På kvällen = in the evening / at nightfall (in general)
På morgonen = in the morning
På sommaren = in (the) summer

Using i with parts of the day would usually sound wrong or very odd:

✗ i kvällen
✗ i morgonen

So you should memorize på + [part of day/season] as a pattern for general time:
på kvällen, på natten, på vintern etc.

Why is it kvällen with -en at the end and not just kväll?

The -en ending makes the noun definite, like English “the evening”.

kväll = evening (indefinite)
kvällen = the evening (definite)

In time expressions, Swedish often uses the definite form where English uses a more general “in the evening / in the mornings”-type phrase:

på kvällen ≈ “in the evening (generally, on evenings)”
på morgonen ≈ “in the morning”
på helgen ≈ “at the weekend”

So på kvällen is a fixed, natural way to talk about what typically happens in the evening.

What is the difference between på kvällen and på kvällarna?

Both refer to evenings in general, but there’s a nuance:

på kvällen
- Literally: on the evening / in the evening
- Often understood as a typical or usual evening in general.
- Very common for generic statements:
  På kvällen är himlen mörk men vacker.
  In the evening, the sky is dark but beautiful.
på kvällarna
- Literally: on the evenings / in the evenings (plural)
- Emphasizes repeated, habitual action:
  På kvällarna går jag ut och promenerar.
  In the evenings, I go out for a walk.

In this specific sentence, på kvällen is perfectly natural. På kvällarna could work too, but it would sound more like you’re talking about a repeated observation on most evenings.

Why is the word order På kvällen är himlen… instead of På kvällen himlen är…?

Swedish main clauses follow the V2 rule: the finite verb must be in second position in the clause, no matter what comes first.

In På kvällen är himlen mörk men vacker:

På kvällen = first element (an adverbial of time)
är = the verb, which must come second
himlen = the subject
mörk men vacker = the rest of the predicate

So:

✔ På kvällen är himlen mörk men vacker.
✗ På kvällen himlen är mörk men vacker. (verb is not second → ungrammatical)

If you start with the subject instead, the order looks more like English:

Himlen är mörk men vacker på kvällen.

Why is it himlen and not himmel?

Himmel is the basic form of the noun (“sky, heaven”).
Himlen is the definite form: “the sky / the heaven”.

Swedish usually marks definiteness with a suffix:

en himmel = a sky
himlen = the sky
flera himlar = several skies
himlarna = the skies

In this sentence, you’re talking specifically about the sky (as a known thing in the situation), so the definite form himlen is used, just like English uses “the sky” in this kind of statement.

Why are the adjectives mörk and vacker in their basic form and not mörka, mörkt, vackra, etc.?

Here, mörk and vacker are predicative adjectives describing the subject himlen:

himlen är mörk = the sky is dark
himlen är vacker = the sky is beautiful

For predicative adjectives (after vara, bli, etc.), the basic rule is:

For an en-word singular subject (like en himmel):
use the base form of the adjective: mörk, vacker
For an ett-word singular subject:
use the -t form: det är mörkt, havet är vackert
For plural subjects:
use the -a form: blommorna är vackra

So:

Himlen är mörk men vacker. (en-word → base form)
Det är mörkt men vackert. (dummy det, neuter → -t)
Stjärnorna är mörka men vackra. (plural → -a)

Why can we say mörk men vacker without repeating är or himlen before vacker?

Swedish, like English, allows you to coordinate adjectives with a conjunction without repeating the verb or subject.

Himlen är mörk men vacker.
Literally: The sky is dark but beautiful.
Understood as: Himlen är mörk men (himlen är) vacker.

You don’t need to say:

✗ Himlen är mörk men himlen är vacker.
That’s grammatically correct but unnecessarily repetitive in normal speech.

This is the same as in English:
“The sky is dark but beautiful”, not “The sky is dark but the sky is beautiful” (unless you want special emphasis).

Why is the conjunction men used instead of och?

men = but, introduces a contrast
och = and, simply adds information

In mörk men vacker, the idea is:

The sky is dark, yet still beautiful (a contrast).

If you used och:

mörk och vacker = dark and beautiful
→ just listing two qualities without highlighting any contrast.

Both are grammatical, but they say slightly different things:

mörk men vacker: Being dark might be seen as negative, yet it’s beautiful.
mörk och vacker: It’s both dark and beautiful, with no implied tension between them.

Can I move på kvällen to the end and say Himlen är mörk men vacker på kvällen?

Yes, that’s perfectly grammatical, and very natural:

Himlen är mörk men vacker på kvällen.

The difference is mostly about emphasis:

På kvällen är himlen mörk men vacker.
→ Emphasis starts with the time: “In the evening, (something is true about the sky) …”
Himlen är mörk men vacker på kvällen.
→ Emphasis starts with the sky, and the time comes as extra information at the end.

Both mean essentially the same thing in everyday use.

Could I also say På kvällen är det mörkt men vackert instead of talking about himlen?

Yes, that’s another very natural way to say something similar:

På kvällen är det mörkt men vackert.
In the evening, it is dark but beautiful.

Here:

det is a dummy subject (“it”), like in English it is raining.
mörkt, vackert are in the neuter -t form because they agree with this dummy det.

Comparison:

På kvällen är himlen mörk men vacker.
→ Specifically about the sky.
På kvällen är det mörkt men vackert.
→ More general atmosphere: it’s dark but (still) beautiful in general.

Both are idiomatic; you just focus on slightly different things.

How do you pronounce kvällen and mörk? They look tricky.

Approximate guidance (not exact IPA, but close):

kvällen
- Stress on the first syllable: KVÄL-len
- kv- is like kv in “kvetch” (or kv in English kv if you know it from loanwords)
- ä like the e in English “bed”, but a bit more open
- -en is a weak “un” sound: a bit like “ehn” but shorter
mörk
- One syllable, stress on the whole word: MÖRK
- ö is like the vowel in British English “sir” or “fur”, but with rounded lips
- The r is usually a tapped or rolled r in many accents, but in Stockholm Swedish it often merges with the following consonant
- k is a hard k, like in “cat”

A rough English approximation:

kvällen ≈ “KVEL-len”
mörk ≈ “murk” but with a rounded eu-type vowel instead of English “ur”

Is there any difference between saying på kvällen and something like om kvällen?

Om kvällen exists but is:

More formal, old-fashioned, or literary in modern Swedish.
Less common in everyday speech than på kvällen.

In normal, contemporary Swedish:

You almost always say på kvällen (in the evening).
om kvällen might appear in older texts or in a poetic style.

So for everyday use, stick with på kvällen.