Raise a toast to solar radiation. The director of the Zurich-based World Radiation Monitoring Center, the organization that measures the amount of solar radiation hitting the ground around the globe, has a strange talent. Give Atsumu Ohmura a glass of white wine and tell him only its vintage, and he'll swish a mouthful and -- without referring to legs, bouquets, or mango backgrounds -- announce where the grapes were grown. His trick? The sweetness of white wine grapes is a function of solar radiation. The more sun a grape plant's leaves absorb, the more sugar the plant produces and the …