Usually you just use "tenki ga ii" for sunny or nice weather soSee, I'm right =) Well, i was saying, "de" is a particle, and the "-te" form of "desu/da". when you want to say something like "It is sunny, and I ate cheese at the resturant." you would use the "-te" form of "desu/da" because it's a compound sentence... "晴れたで、レストランでチーズを食べました。"right? (I don't know if the sentence is correct, but you get the point)
Usually you just use "tenki ga ii" for sunny or nice weather so
天気のよい日で、（天気がよくって。。。）レストランでチーズを食べました。is OK,
but still sounds a little funny.
私は教師で、あなたは消防士です。is another example -- functionally similar to て
for verbs and i-adjectives used in this case as a connector for nouns or na-adjectives. で has other more complicated uses as well but hopefully this will settle scores to a draw for now. Luckily nothing more damaging came of this little tiff..
で can be either a particle, or the ～て form of だ. It cannot be both at the same time; its use is determined by context.
As a particle, で is very widely used. It not only can be used to indicate the location in which an action takes place, but it can also infer the means by which a verb is accomplished.
レストランで食べましょうか。 Shall we eat at a restaurant?
教室で試験を取った。 We took a test in the classroom.
お箸で食べられません。 I can't eat with chopsticks.
車で迎えに来てくれればいい。 It'd be good if you picked me up by car.
As the ～て form of だ, it is only used to link clauses in sentences from what I've seen. (note: the ～て form of a verb is not informal, it is widely used in sentences of all sorts). In this capacity is is less often used than the particle で.
Like Elizabeth said,
天気がいい日で、 It is a nice day (weather-wise), and
天気がよくて、The weather is nice, and
essentially achieve the same end. A noun or な-adjective calls for で, whereas いい／よい is an い-adjective, and has its own ～て form.
Is it possible for 試験 take 取る as a literal translation of教室で試験を取った。 We took a test in the classroom.
Tomii -- There are various ways of using 晴れ the noun that I think work as well such as （今日は、空は）晴れ、（晴れの日で）レストランでチーズを食べました。but that are unusual in real conversation because normally this level of vocabulary is reserved for the weather forecast...晴れて(or 晴れていて)、レストランでチーズを食べました。
would be "it was sunny and I/we ate cheese at a restaurant." the sentence itself is weird, but grammatically fine.
晴れ is a noun meaning clear or clear weather.The use of "晴れ、" is a different, more formal way of linking clauses through stem forms of the verb. Best not to add too much new forms and confusion to the mix, I think.
Yes, you're probably right that 晴れの日 doesn't work. Perhaps I was thinking of the usual expression "hareta hi".It is also the stem form of 晴れる, so it seemed that your sample sentence was using that to link the clauses.
Not 晴れの日で, where the use is clearly a noun, but 今日は晴れ、レストランで食べました。
Actually thinking a bit more about this.... 晴れの日 (perhaps without the "de" although that isn't a distinction I'm completely comfortable with) I'm sure I have seen examples of used and will ask but don't appreciate offhand why it wouldn't be usable for "clear day".It is also the stem form of 晴れる, so it seemed that your sample sentence was using that to link the clauses.
Not 晴れの日で, where the use is clearly a noun, but 今日は晴れ、レストランで食べました。
OK, in my state of zombie-like state of sleeplessness that was my miswritingOh, I was just talking about the use of 晴れ the noun versus 晴れ the stem-form of the verb, not the popularity of its use. Grammatically I don't see anything wrong with 晴れの日, other than there are several other ways of saying the same thing which seem to be more common.