What if there were no hurricanes or tornoadoes?It's a nuisance when it rains on a picnic. It's a tragedy when a tornado destroys a neighborhood. But our planet would be a very different place if it did not have extremes of weather. Some plants can grow only in hot, dry conditions; others require cold temperatures at certain times of year. And if the Arctic and Antarctic were less cold, melting ice would raise sea levels around the world and...