It's Flu Season - Why in Winter?

The New York Times ran a great article about a study that answers an age old question. Why does the flu (influenza) season always happen in the winter? We seldom see flu in Summer or even the Fall. In the tropics flu doesn't even exist.There have been hypothesis that it was from overcrowding in schools and homes, or in the winter people are stuck inside and can pass the germs. But people are