If its title is to be taken to heart, Michael Gordon's Weather follows climatic patterns over years, not a single storm or an evening snowfall. It's waves of activity are predictable only in a very coarse sense and seem indeterminate in detail. Winds pick up and die down like day followed by night, varying in intensity and duration. Changes overlap and are indistinct, as the sun comes out before the rain lets up, like cold summer nights and warm winter days. But they are still of a sort, still environmental, still weather. Weather itself isn't violent, pleasant or heavy. Those are human experiences of weather, and Gordon's piece is more about weather in its pure state, without interpretation. It's not Sunday in the Park with George. It is, perhaps, more the experience of the clouds than of the people below.

Gordon's piece is scored for 16 string instruments, in this performance and on the Nonesuch recording Germany's Ensemble Resonanz. While the remarkable 1998 record is heavy on post-production - filled with thunder and thick studio effects and, as it passes the halfway mark, loud air raid sirens - the concert version was performed naked, just strings and, bravely, without a conductor. The stripped-down live presentation was less overt without the contextualizing sound cues, but all the more effective for it. The scored effects, players falling out of sync to create delayed echoes and "artificial" loops - stood out when removed from the devices of the disc.

Which is why the third movement - in the concert version as well as on the recording - is such a shock. The onslaught of sirens moves the music abruptly from the etherea and into its ramifications. Images are conjured of children trying to get home from school, of airplanes trying to land. The orchestra donned headphones for the movement, for technical purposes no doubt but in a sense putting them in a more reactive context as well. The layering of strings and sirens works to stunning effect even in the context of suggested emergency, although it was far too quiet, the danger too distant, in the concert hall. (The cd, at extreme volumes, has a tense beauty.)

Storms subside, but weather doesn't. Weather neither stops nor cares, and it doesn't take note of felled trees or flooded streets, it just proceeds. The final movement recalled the first with a similar repeated line for cellos and bass and darting violins on top.

The four movements could be taken to suggest a year's cycle, as in Vivaldi's Four Seasons. But it's not as simple as that, at least not on the ozone-depleted, warmed globe of the 21st century. (And Gordon, in fact, politely dismissed such a connection in an onstage discussion that preceded the concert, saying "I can't say I worship at Vivaldi's feet. I worship at Bach's feet."). Gordon's Weather might be the soundtrack for a more erratic, and perhaps less humane, annum.