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Name: _____________________________________________ Period: ______ Earth’s Interior Directions: Read (re-read) the following information. Use the information in the reading to complete the following questions. Upon completing this assignment you will be allowed to reassess Learning Target (LT) 2: Heat Transfer. Heat is transferred to the surface of the Earth from the hot Earth's core by conduction and from radiation from the Sun. The atmosphere is heated by absorption of some of the electromagnetic radiation from the Sun, and contact with the warm surface of the land and water. The warm land and water also radiates infrared, some of which is absorbed by the atmosphere, adding to its thermal energy. The remaining heat on the surface is sent out into space in the form of infrared radiation. So what causes the plates to move? It turns out to be a consequence of the high temperatures inside Earth. Common experience tells us that heat flows from hot to cold, so the heat in Earth's deep interior must be flowing somehow to the surface. Hot lavas and gases coming out of volcanoes are direct evidence of heat flowing out of Earth. Another indicator of heat flow is the increase in temperature with depth inside deep mines. These measurements of heat flow, however, are all made near the surface. The processes by which heat moves in Earth's deep interior are investigated by computer simulations, which can be compared with seismic and heat flow data that show temperature variations in Earth's interior. Both measurements and simulations show that the hottest part of Earth's interior is the iron core. Part of the heat down there is actually left over from the fiery formation of Earth; part is from latent heat released by the freezing of liquid iron in the outer core onto the solid inner core, and part is (possibly) from the slow decay of naturally radioactive elements like uranium and potassium mixed in the core. The core heats the bottom of the rocky mantle. The hottest rock near the bottom of the mantle becomes slightly less dense than the somewhat cooler rock above it, so buoyancy forces try to push the hottest rocks upward. Although the rock in the mantle is solid, the pressures and heat are so great that the rock can deform slowly, like hot wax. So the hot rock creeps upward through the cooler rock. As the hot rock rises, cooler rock flows downward to take its place next to the core, where it is heated and becomes buoyant enough to rise again later. The rising hot rock comes in contact with cold rocks near the surface of Earth where it gives off its heat, cools, and sinks again. Most of the rock in the mantle moves in this broad cyclic flow, indicated by the arrows in the figure. This zone, where rock is soft enough to flow, is called the asthenosphere. This means of heat transport--the cyclical movement of hot and cold material-is called convection. Occasionally, however, masses of hotter-than-normal rock rise independently of the broad flow, like bubbles through a flowing stream. These masses of very hot rock form rising columns with rounded tops, called plumes. Rock near the surface of Earth is so cold and at such low pressures that it cannot flow like mantle rock. So how does heat get through this rigid layer lithosphere, to the surface? At the top of the asthenosphere, the hot rock flows along the bottom of the lithosphere, transferring its heat to the cold rocks by conduction. The heat then flows through to the surface, again by conduction. A second way of getting heat through the lithosphere is more exciting: melt some of the mantle rock and let it flow through cracks in the lithosphere to the surface! Sound familiar? Places where liquid rock (lava) flows onto Earth's surface are usually called volcanoes! Describe what direction heat get transferred from one object to another. ______________________________________________________________________________ What are the three ways in which heat is transferred from one object to another? 1. 2. 3. Earth has an internal and an external heat source. What is Earth’s external heat source? ______________________________________________ How does the energy from this source reach the Earth? (circle the appropriate answer/s) Conduction Convection Radiation What is Earth’s internal heat source? _______________________________________________ How does the energy from the inner core reach the outer core? (circle the appropriate answer/s) Conduction Convection Radiation How does the energy from the outer core reach the mantle? (circle the appropriate answer/s) Conduction Convection Radiation How does the energy from the outer core travel through the mantle? (circle the appropriate answer/s) Conduction Convection Radiation How does the energy from the mantle reach the crust? (circle the appropriate answer/s) Conduction Convection Does the crust only receive heat from the mantle? Radiation Yes No Explain your thinking. ___________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ ______________________________________________________________________________ Comments: __________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ Next Steps: Retake LT Revisit and Revise Get More Help