It's damn cold outside, the kind of Chicago freeze that makes you feel like you're walking through a meat locker. When the weather gets this frosty, and especially during the daytime, I tend to default to ambient music, which somehow straddles the line between the bracing blood rush of unearthly wind and the calm that emerges from being in those kinds of temperatures for an extended period of time. It's fitting that Brooklyn ambient duo Mountains (Koen Holtkamp and Brendon Anderegg, who are both SAIC graduates) tend to release their albums during the winter, because that's often when it sounds best. I've been listening to their latest LP, Centralia, quite a bit, and as with their kosmische-indebted 2009 album, Choral, it's another noticeable and welcome development in their sound. Unlike Choral and its follow-up, last year's Air Museum, Centralia relies less on processed guitars and emphasizes more acoustic instrumentation, a return to some of their earliest work. On "Circular C," piano and guitar shimmer over the distended guitar tones that underlie most of Mountains' music, hypnotically snaking through a percolating keyboard loop and psychedelically mutating drones. Centralia is out now on Thrill Jockey, and with the albums on that label, I recommend going with the vinyl version if you can swing it.