Led Zeppelin pretty much wrote the book on thundering riffs and deafening shrieks, but the hard rockers are also gifted in using space and atmospherics. These qualities come out in some of their folky songs, as in the quietly droning raga “Black Mountain Side” and the dreamy “That's the Way.” But those ethereal qualities also appear in the Brits' electric epics, including “In the Light,” which glows like a cosmic ray.