[He shrugs toward the door.]

Out thereish. Or well, that's where it started-- I had to find the closest bit of water. It'd be a better snow if we were in a room with taps--better still if we were outdoors. It needs a bit of water to work with, from somewhere nearby--if it's in the same room as the water, all the better for it, otherwise it has to draw from somewhere else and get transported here, and then you do the freezing charm, but it's hard work, keeping all of that up at once, so it all gets quite complicated--

[He gives her a rueful little grin, and another shrug.] Better to say it's magic and leave it there.

[And while he's not the best at reading people--well, most of the time, that's down to sheer inattentiveness. Because at times like this, when it really seems to matter, he can glance over at her, and watch her watch the snow, with a far clearer expression than she'd worn before. And that feels like a victory, even a small one, and he cocks his head at her, slightly.]

I mean, I can go on and explain it if you like. Most people don't care. Me, I'd rather just watch snow falling than talk about anything much.