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.