There is a very brief description of the people shoveling snow from off their roofs (which I need to do myself) that is short but tells a good deal about their sense of happiness on Christmas Day.
Though the townspeople are atop pitched roofs and working hard to remove inches of snow (I hope it's a dry snow), which is a precarious position to be in and difficult work to do, they were "jovial and full of glee; calling out to one another from the parapets."
First of all, jovial means "hearty, joyous humor." So they weren't just happy, they were ready for some fun and laughter. Secondly, glee means "open delight and pleasure." So, not only were they ready for fun and laughter, they were openly delighted and experiencing pleasure--even in roof-snow shoveling!
To prove this description of the townspeople and to give a solemn seal of truthfulness to the exuberantly happy feelings abroad on Christmas Day, Dickens proceeds to say that the townspeople, unable to contain their cheerfulness, are hurtling snowballs at each other and having a good laugh over the sport no matter which way the snowball flies. (Picture mom and dad on the roof throwing snowballs at the neighbors on Christmas morning!)