 Cooling your body on a hot day is important. You can do the cooling voluntarily, or you can let your body do it all by itself. Here's how. 
One way to cool off is to drink or eat something that's a lot cooler than your body temperature. Your body needs to replace the moisture it lost through sweat, and this is one way to help. But taking the cold liquids or solids into your body will also help to cool you directly.In fact, eating ice cream is an excellent way to cool your body from the centre out. The moment the ice cream enters your mouth, it begins to melt. This is the process of changing a solid to a liquid, which requires energy. The energy comes from your body ... which means heat is moving from your body into the ice cream. You get cooler. As the ice cream melts, and finds its way to your stomach, it's still cold. Eventually your stomach contents will warm up to body temperature ... but to do this, heat must be drawn from your body. All this heat being used to warm up the ice cream will make your stomach cooler. Blood flowing in and out of the stomach lining will lose heat to warm the stomach, making the blood cooler. This cooled blood now gets circulated around your body, cooling it everywhere!  Your body can cool itself by sweating too. Here's how it works. Moisture is released onto the surface of the skin. The heat from your arm, which is provided by the blood flowing through it, is used to turn the liquid water into a gas. The water evaporates. But the heat needed to do this comes from your arm and the blood flowing underneath the skin, so the blood gets cooled. This cooled blood in turn gets pumped all around the body, making your whole body cooler.  Using a fan can make you feel cooler, even if it's only blowing warm air. Sweat turns into water vapour when it evaporates, but a given amount of air can only hold so much moisture ... after the air gets 'waterlogged' with water vapour, very little evaporation can take place. That's why it's hard to get cool on a hot humid day ... the air is already full of water vapour.Using a fan pushes a lot of air past your skin. As your sweat evaporates, the air and water vapour is immediately blown away, to be replaced by new drier air, which allows evaporation to continue. |