★★ Clean clouds, blank as paper, floated on the sky seen from bed. They gathered into something unpleasant, another of late winter’s near-daily interludes of gloom, carrying past the season’s end. Midafternoon unexpectedly broke it, though, and the streets filled with sun again. Aged trash was in the treetops on Broadway but leaves were in the trees on 72nd, and there was a persistent soft edge to the cold. Not persistent enough, though. In the course of a piano lesson the light and softness departed completely. A truck laden with salt turned the corner, calcium chloride fluid sloshing in its translucent tanks. One palm frond lay in the street. By bedtime there were snowflakes passing in the lights, whitening the upholstery on the luxury building’s rooftop chairs.