But does puffing on hot food really help to cool it off, or are you just moving hot air? The answer: Yes, and yes. When you blow air over piping hot food, you're sending air close to your body temperature—an average of 98.6 degrees—and using it to replace warmer air in a process known as convection.

Yes, blowing on a hot object cools it down through two primary physical processes: convection and evaporation. First, the air immediately surrounding a hot cup of coffee, for example, is heated by the liquid, creating a "blanket" of warm air that slows down further heat loss. When you blow, you physically push that warm air away and replace it with cooler ambient air, which can then absorb more heat—this is called forced convection. Second, if the object is a liquid, blowing increases the rate of evaporation. As the fastest-moving (hottest) molecules escape the surface as steam, they take their heat energy with them, leaving the remaining liquid cooler. Interestingly, blowing is most effective when the air you blow is significantly cooler than the object; if you were to blow air at 100°C onto 80°C soup, you would actually be heating it up!