Thinking that this answer is rather long, I will…
submit it nonetheless.
Ich bitte um Verzeihung nicht frueher geantwortet zu haben. Ich habe tatsaechlich viel darueber nachgedacht und begann sogar eine Kleingrammatik ueber das Gerundium zu schreiben, aber dann fiel mir ein, dass jeder Deutsche, der je Englisch gelernt hat, schon viel darueber in den Refernzebuechern hat, die im Buecherregal stehen. Auch merke ich, dass Du meinst, meinstens erfolgreich mit dem Gerundium umgehen zu koennen. Bloss dieses einzige Exemplar bereitet Dir Schwierigkeiten, vermutlich. Also, zuerst ein paar allgemeine Bemerkungen, die Du wohl schon weisst und dann zu der Hauptfrage. Ich werde so frei sein, die Antwort auf Englisch zu schreiben, meistens, weil ich so eine Erklaerlung 20mal schneller in der Muttersprache schreiben kann (and speed could be of the essence, being that my hard drive just started making unfamiliar and terrible noises a few minutes ago) und zweitens, in der Glaube, dass diejenigen, die diese Antwort interessieren wuerde, sicherlich soviel und noch mehr Englisch verstehen koennen.
In a sentence such as “Coming into the bedroom, Alice saw that the waterbed had sprung a leak.” it is clear that the meaning in German could be translated with a dependent clause beginning with a word such as “waehrend,” “als,” ”gerade als,” “indem” and maybe there are a few others also. The meaning of the sentence is clear: the action taking place in the dependent clause (“coming into the bedroom”) is taking place at the same time as the action in the main clause of the sentence (“saw that the waterbed had sprung a leak”) It might be helpful to look at this as a way of accomplishing in english the equivalent of a german sentence such as “Die in das Schlafzimmer kommende Alice sah…” Of course a literal translation of: “The in the room coming Alice saw…” is not possible.
I believe that most such sentences will cause germans few problems. However, it is worth mentioning that even native speakers can get into trouble stylistically, if they are not careful. An example might be: “Doing more poorly at math that the rest of the pupils, the teacher was concerned about Ralph.” The writer most surely meant that Ralph did more poorly at math than the rest of the pupils, but the sentence actually says that the teacher did more poorly at math than the pupils. Clearly, to avoid trouble, you will want to use only sentences in which a dependent clause with such gerund phrasing clearly modifies the subject of the main clause. Often such examples are quite humorous - such as: “Weighing more than three tons, the lady drove the truck slowly and carefully.” “Being likely to throw feces, visitors at the zoo are cautioned not to tease the gorillas.” “Smelling like old, wet socks, French gourmets nonetheless relish these cheeses.”
Now, to consider the gerund “being.” Here, the meaning of the dependent clause changes from “waehrend,” “als,” und “indem” to “weil” and maybe also “indem, dass.” So the sentence “Being such a miserable day, I decided to stay in bed.” means “because it was such a miserable day, I decided to stay in bed.” As noted before, it is possible to say:
What with it being such a miserable day…
With it being such a miserable day…
It being such a miserable day…
Being such a miserable day…
To me, all these possibilities sound and mean the same. I hear no appreciable difference between them in meaning. At most, there might be a difference in tone in that if I were at costume party dressed up as a cliche hillbilly (backwoodsman) from the southern Appalachian mountains, I might choose “What with it being…” My perception is that such usage would be more common there - and that would make sense since the people there often use phraseology that is more conservative and to some extent still elizabethan (Shakespearean) english. However for your purposes (being a non native-speaker), I would choose “It being…”
Probably the best way to think of this phrase is to think of „it being“ as an idiomatic usage which expresses causality - it means simply: “because…” Of course this brings us full circle back to your original phrase which you needed to rewrite: “Because it was such a miserable morning…” It being an idiom, I do not believe that I can give you a german equivalent that would make any sense it all. It being an idiom (if I am right about it being an idiom) you will just have to memorize its usage. It being the case that “it being” means “because” maybe this will not be too hard. In fact, it being the case that you can always express an “it being” phrase differently, you can confidently avoid the usage completely in everyday life.
Be aware that the “it” in the sentence we are discussing is there because the gerund phrase does not refer to the subject of the main clause (I am not a miserable morning.) But if you say: “Being sick, I stayed in bed.” it is clear that the “I” of the main clause is sick. It would be totally wrong to say “It being sick, I stayed in bed.”
Further examples:
Being hungry, I ate lunch.
It being noon, I ate lunch.
Being colorful, the autumn trees are beautiful.
It being autumn, the trees are colorful. (or colourful, if you wish. Mir egal.)
Being a determined kayaker, he will try to win the race.
It being the Olympics that the race is in, he will need to be a determined kayaker in order to win the race.
Note that the verb in the main clause can be any tense.
Being that I have written far too long an explanation, I will stop now. Wishing you much success with the gerund, I will send this answer now. I will check back, hoping that you will tell me if anything remains unclear.
Jim