"Yağmur yağdığı zaman kitap okumak istiyorum."
Translation:I want to read a book when it rains.
Could this sentence also be expressed this way?:
Yağmur yağdığında kitap okumak istiyorum.
Not quite...that would only have the meaning of "once it rains," and that sounds really weird in Turkish and in English.
"while" isn't accepted instead of "when" - is there a nuance here that causes this not to translate properly?
As a native English speaker, I would say that "while" and "when" can often be used interchangeably, but there is a slight difference. You can Google "difference between while and when" for more opinions, but here's mine: "When it rains" is the same as "whenever it rains." "When I visit my in-laws, I always bring a dessert." We often use "while" with continuous tenses to emphasize an interruption: "The phone rang while I was taking a shower." "While" is also used when two longer actions are simultaneous: "While you're cooking dinner, I'll straighten up the living room." If you said, "I like to read while it rains," I would understand you, but it sounds awkward. Use "when" when the meaning is "whenever."
I meant a nuance in the Turkish, not the English. I'm American. ;)
"I like to read while it rains" is of course ungrammatical--at least in most dialects--but as far as I know, the participial form "yağdık" doesn't immediately imply or exclude the progressive tense, so I don't see why "while it's raining" isn't an acceptable translation for "yağmur yağdığı zaman," since it's literally "(in) the time characterized by raining."
The reason it struck me as odd is because "I want to read a book when it rains" doesn't make much sense. Wanting is somewhat of a one-time phenomenon, and indeed that's why Turkish uses the progressive tense. It might work in context, but at least for me it makes more immediate sense to think of the sentence as "I want to read a book while it's raining," implying that it's going to rain soon and I plan to read a book throughout the duration of the storm.
Sorry! My mistake! English teacher's disease. I'm trying to get a handle on the verbs that can be progressive in Turkish that usually are not in English. We obviously can't translate "istiyorum" as "I am wanting" in this sentence. I suppose I was thinking of it as "Whenever it rains, I find myself wanting to read." But I can see your idea that the rain is imminent, and I'm planning to read during it.
I suppose we should have used article 'a' if there were 'kitabi'. But the word in that sentence is 'kitap', so it means any book, not a definite one. Can anyone explain me that?
If you use the accusative case, it is a definite direct object (you would normally use "the" but not always).
"a" is general.