First, lets tackle mixing puffs. When cool air moves over warm water, the air is heated from below, causing warm air to rise and cool air to tumble down to take its place. This is why winds can increase so dramatically over the Gulf Stream when cold air moves off the U.S. east coast. The additional turbulence mixes faster-moving air down to the surface. The mixing process is not a simple one, where the entire atmosphere mixes down all at once. Instead, it takes on a random nature and these downward tumbles occur in spurts, or puffs. The larger the temperature difference between the air and the water, the stronger and more frequent the puffs.