It was pouring when Charles Grene got home to Westminster on Sunday. He dialed the weather phone; the relative humidity was 79 percent. The Weather Channel said it was 81 percent. He's puzzled: "I thought that when it is raining the relative humidity was 100 percent." It is, Grasshopper, at least up where the water vapor is condensing. But the air is often drier at the surface, around our instruments. Raindrops can evaporate as they fall, producing veil-like clouds called "virga."