This 23-year-old composer paints a unique fog of fragile melancholy using the tiniest of brushes — weightless drones, pianos pressed with a feathery touch, bows barely scraping strings, and electronic bliplets that sound like submarines cooing in the murky distance. His second full-length has an impossibly gentle feel that makes fellow Icelandic drift merchants like Sigur Rós and Jóhann Jóhannsson sound downright leaden. Arnalds’ game is more ambience than transcendence — so the four very brief detours into Explosions in the Skystyle post-rock seem all the more cinematic.