I woke up briefly at four this morning to an unpleasant sound. Stumbled to the window, looked out, turned to the cat and asked, "Should snow hiss?"
I'm now at work. The heat has kicked into overdrive to deal with the falling temperature. The great big air-intake vent on the far side of the room is making this whistling noise. It's constant, though there are variations in pitch and intensity. Imagine a cross between between an unattended whistling teapot and a howling windstorm. I feel sorry for the folks right in front of the vent.