Convection Currents and the Mantle • OBJECTIVES: – Explain how heat is transferred – Identify what causes convection currents Radiation • The transfer of energy through empty space • Examples: -Sunlight -Open flame Conduction • Heat is transferred by direct contact of particles of matter • Heat travels from hot to cold • Examples: – Hot frying pan, Fire poker stick Convection • The movement of a fluid, caused by differences in temperature and density, that transfers heat from one part of the fluid to another • Examples: -Heating water -Mantle in the Asthenosphere -Air --wind Checkpoint-1 • What are the three types of heat transfer? ANSWER-1 • RADIATION • CONDUCTION • CONVECTION Checkpoint-2 • Describe how convection currents form? ANSWER-2 • The heating and cooling of a fluid changes in a fluid’s density, and the forces of gravity combine to set convection currents in motion. Checkpoint-3 • In general, what happens to the density of a fluid when it becomes hotter? Answer-3 • In general, when a fluid is heated, its density decreases. --i.e.steam and ice Checkpoint-4 • What happens to convection currents when a fluid reaches a constant temperature? ANSWER-4 • When a fluid reaches a constant temperature, the convection currents stop.