Scratch Cat is lost in the forest! To keep warmth he must start a fire. But while on his journey for survival, he makes an interesting discovery about Convection...
In a liquid or gas, convection happens because of how particles react to heat. When fluid particles at the bottom are near a heat source, they gain energy and start to move much faster. As they zip around, they push away from each other and spread out. This makes the warm fluid "lighter" or less dense, which causes it to float upward toward the top. As these fast moving particles rise and get further away from the heat, they begin to lose their energy and slow down. Because they aren't moving as fast anymore, the particles crowd closer together, making the fluid more dense again. This heavy, cool fluid then sinks back to the bottom. Once it's at the bottom, it gets heated up again, the particles speed up, and the whole cycle called a convection current continues over and over.
