A Christmas Carol is a novella written by Charles Dickens. It was first published in 1843 and follows the story of Ebenezer Scrooge. Ebenezer Scrooge hates Christmas and everything that comes with it, but through his encounter with the Ghosts of Christmas Past, Christmas Present, and Christmas Yet to Come, he completely changes and becomes a different man.
Setting often plays a crucial part in subtly helping the reader to understand the plot of the story. For example, the setting can give you a clue about a person's social standing, the time of year, or even the time of day without it needing to be explicitly pointed out as part of the dialogue. A Christmas Carol is no exception.
In paragraphs five and six, we read that Scrooge had to "rub the frost off with the sleeve of his dressing-gown." This is a clear indication that the weather must be really cold, which would explain the existence of frost. Furthermore, this description tells us that Scrooge is probably already in a bad mood after waking up, as waking up in such low temperatures can't have been nice. This forms a contrast to the Scrooge we encounter at the end of the play, who is much happier.
We also read that there was "no noise of people running to and fro," which is an indication that the day hasn't started yet. This helps the reader picture at what time the beginning of stave 2 is set, which explains to the reader why Scrooge is so baffled by the fact that it is still night.