Environmental Science Heat Transfer Environmental Science

Heat Transfer Heat always moves from a warmer place to a cooler place Example: If you put a hot cup of coffee into the refrigerator, heat energy from the coffee will travel to the refrigerator. Heat transfer warmer cooler

Methods of Heat Transfer There are THREE methods of heat transfer CONDUCTION CONVECTION RADIATION

Conduction A transfer of heat through direct contact On a molecular level, warmer molecules are vibrating faster than cooler ones. When they come in contact, the faster moving molecules “bump into” the slower moving ones and heat is transferred.

Conduction Examples The heat from a hot liquid makes the cup itself hot. An ice cube will soon melt if you hold it in your hand. The heat is being conducted from your hand into the ice cube. After a car is turned on, the engine becomes hot. The hood will become warm as heat is conducted from the engine to the hood. A metal spoon becomes hot from the boiling water inside the pot.

Convection Travels through fluids Creates convection currents warmer / less dense materials rise, cooler / denser materials sink

Convection Examples Hot air balloon – heated air moves upward, causing the balloon to rise. The pilot releases some of the hot air and cool air takes it place, causing the balloon to lower. Boiling water - The heat passes from the burner into the pot, heating the water at the bottom. Then, this hot water rises and cooler water moves down to replace it, causing a circular motion.

Radiation Heat energy that travels as an electromagnetic wave (no medium) This is how heat from the sun reaches Earth

Solar Radiation

Heating of the Ocean Heat from the sun is ABSORBED by the ocean This heat is then transferred by OCEAN CURRENTS