Learn Hardcore Turkish: Pencereden esinti gelince balkonda rahatça oturabilmek güzel. - When a breeze comes through the window, being able to sit comfortably on the balcony is nice.

Pencereden esinti gelince... = when there’s (some) breeze from the window...
Pencereden bir esinti gelince... = when a (particular/sudden) breeze comes from the window... With bir, it can feel a bit more like a specific instance.

Is esinti gelmek natural, or should it be rüzgâr esmek?

Both are fine, but they focus differently:

Pencereden esinti gelince highlights a breeze “coming in” through the window (direction/source).
Rüzgâr esince = “when the wind blows,” more general, no source implied. You can also hear esinti esiyor (“a breeze is blowing”), but with a source, gelmek sounds very idiomatic.

Why gelince and not gelirken?

-ince/-ınca = “when/once” (time point or condition). It marks the time that something happens.
-irken = “while/as” (ongoing simultaneous action). Here, the idea is “when a breeze comes (i.e., once it starts),” so gelince is preferred. Gelirken would suggest “while the breeze is (in the process of) coming,” which is odd.

Could I say geldiğinde instead of gelince?

Yes: Pencereden esinti geldiğinde... is fully correct and a bit more formal/literary.

gel-diğ-in-de = verb stem + -dik nominalizer + 3rd person possessive + locative “in/at,” literally “at the time of its coming.”

Should there be a comma after gelince?

Recommended: Pencereden esinti gelince, balkonda... A comma after an adverbial clause is standard in writing, though in short sentences it’s sometimes omitted.

What does balkonda express?

balkonda = balkon + -da (locative) = “on/at the balcony.” The locative -da/-de/-ta/-te follows vowel harmony and consonant voicing; after n you use -da.

Why use oturabilmek instead of oturmak?

-ebil- expresses ability/possibility/permission. With the breeze, conditions allow it, so:

balkonda rahatça oturabilmek = “to be able to sit comfortably on the balcony.” If you say oturmak (“sitting”), you describe the activity itself as nice, not the newly enabled possibility.

Why isn’t oturabilmek conjugated?

Here it acts as a verbal noun (an infinitive) and serves as the subject of güzel:

“(Being able to sit comfortably on the balcony) is nice.” You can personalize it with possessive:
Balkonda rahatça oturabilmem güzel. = “My being able to sit... is nice.”
Bizim balkonda rahatça oturabilmemiz güzel.

How would I say “I can sit comfortably on the balcony when there’s a breeze”?

Pencereden esinti gelince, balkonda rahatça oturabiliyorum.

What’s the nuance between rahatça, rahat, and rahat rahat?

rahatça: adverbial, standard “comfortably.”
rahat: often used adverbially in speech; also fine: rahat oturmak.
rahat rahat: colloquial intensifier, “really comfortably/at ease.”

Who is the subject of gelince in this sentence?

It’s esinti. In Pencereden esinti gelince, the breeze is what “comes.” The main clause doesn’t need to share the same subject.

Can I change the word order?

Yes. Common options:

Pencereden esinti gelince, balkonda rahatça oturabilmek güzel. (most natural)
Balkonda rahatça oturabilmek, pencereden esinti gelince, güzel. (acceptable; keep the comma) Placing the time clause first is the default and smoothest.

Could I replace güzel with other words like hoş or keyifli?

Yes, with slight nuance:

hoş = pleasant, nice.
keyifli = enjoyable, relaxing.
harika = great/wonderful. Example: ...oturabilmek hoş/keyifli/harika.

Why is there no “it” in “it’s nice”?

Turkish doesn’t use a dummy subject. The verbal noun phrase balkonda rahatça oturabilmek is the subject, and güzel is the predicate: “(Being able to sit...) is nice.”

When would I use güzel oluyor instead of güzel?

güzel states a general fact/opinion.
güzel oluyor suggests a repeated or specific situation/event: “it turns out/ends up being nice (when that happens).” Example: Pencereden esinti gelince, balkonda oturmak çok güzel oluyor.