Though not based on the typical King Arthur legend (no Lancelot or Guinevere here), Henry Purcell’s opera still features plenty of magic and intrigue. In this “Frost Scene,” one of Arthur’s enemies transports the action to a freezing snowscape, and we listen as the local people (headed by a grumpy winter spirit sung by a bass vocalist), lament the bitter cold. Purcell paints a vivid picture of the scene by having the instruments and singers perform almost exclusively in short, choppy notes (known as staccato, stah-CAH-toh) that mimic shudders and shivers. In fact, Purcell often has his chorus and soloist sing one word over several quick notes to emphasize the frozen climate, as when they sing, “co-o-old.” Sounds as though they’re actually shaking in the snow, doesn’t it?