Interiors of Worlds and Heat loss

Transcription

1 Interiors of Worlds and Heat loss

2 Differentiation -materials separate into layers by gravity

3 How do we learn about planetary interiors? Measure moment of inertia & average density Observe seismic events Study planetary magnetic fields

4 Interior of our planet gaseous atmosphere (lowest density)

5 Interior of Terrestrial Worlds

6 Interiors: Gas Giant v.s Terrestrial

7 Interior of Gas Giant Worlds The magnetic fields of gas giants indicate that there are large amounts of circulating, electricallyconducting materials. Metallic hydrogen or water

8 Which of the following layers of a planet is not characterized by its density? A.core B.mantle C.lithosphere D.crust E.none of the above 2014 Pearson Education, Inc.

9 Heat loss

10 Planets gain their initial internal heat energy when they first form

11 Planet spend the rest of their lives losing internal energy to space

12 3 Types of Heat loss Conduction -atoms vibrate strongly causing atoms next them to pick up energy Convection- heat causes fluids to move, the hot fluid rises, the cold fluid sinks. Radiation- photons of electromagnetic light carry energy away from the object

13 Which Forms of Heat Loss Work Where? All worlds conduct inside. All worlds radiate out to space (the only heat transfer that works in a vacuum!). Larger worlds convect inside. Largest worlds convect and radiate inside. (wavelength of radiation depends on world mass)

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15 Solid Convection Causing Volcanism

16 Solid convection causing movement, but no crustal break-up

17 Solid convection causing crustal break-up (Earth only)

18 How does an object's rate of cooling vary with size? A. A larger object cools more slowly than a smaller object. B. A smaller object cools more slowly than a larger object. C. Size has no effect on an object's rate of cooling Pearson Education, Inc.

19 Geologic Processes

20 Geological Processes Tectonics Rocks bend and break (folding and faulting). Volcanism Materials melt, explode and freeze. Erosion and surface processes Surfaces flatten out: mountains crumble and holes are filled in. Mass wasting (gravity action) Wind action Water action Impact Cratering (external) Bodies from space hit the ground, making a hole.

21 Tectonics -Folding When rocks are squashed they will compress and bend away from the direction of maximum pressure

22 Tectonics -Faulting 1. Extension Faults -crust moves apart, makes a larger area. 1. Compression Faults -crust moves together, makes smaller area. 1. Strike-slip Faults -crust moves sideways, no gain or loss of area

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24 What is true of convection that stresses a planet's crust? A. Mountains may form where the crust is pushed together. B. Cracks and valleys may form where the crust is pulled apart. C. Convection has no effect on a planet's crust. D. A and B 2014 Pearson Education, Inc.

25 Volcanism Materials melt, erupt and explode, then freeze and coat the surface

26 Generic Volcano Structure

27 Volcanic Processes Rocks melt and explode. 2 components: lava, gasses Lavas - variable viscosity,depending on chemistry Low viscosity (runny lava) range of viscosity (gooey, sticky lava) Low gas content Result: Low broad shapes Volcanic Shield Floods Volcanoes High viscosity High gas Result: rangeofvolcanoes Cinder cones Tall cone shapes Stratovolcanoes

28 Volcanic Floods -VERY low Viscosity

29 Hawaiian Effusive eruption

30 Olympus Mons Martian Shield Volcano Note the broad shield shape and the central cauldera

31 Volcanic Processes Rocks melt and explode. 2 components: lava, gasses Lavas - variable viscosity,depending on chemistry Low viscosity (runny lava) range of viscosity (gooey, sticky lava) Low gas content Result: Low broad shapes Volcanic Shield Floods Volcanoes High viscosity High gas Result: rangeofvolcanoes Cinder cones Tall cone shapes Stratovolcanoes

32 Explosive Stratovolcanos Occur only on Earth a product of plate tectonics

33 Alternative Materials carbonatites, East Africa, Earth Water eruption plume, Enceladus sulfur volcanoes, Io

34 Erosion and Surface Processes Gravity pulls everything into a smooth sphere. Thus, surfaces flatten out: mountains crumble and holes are filled in. The processes that carry out erosion each show characteristic patterns that we can see on Earth and on different worlds: Mass wasting (gravity action)- land slides Wind action- sand dunes, wind streaks Water action- river channels, ocean shores, glacial erosion

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36 Sand Dunes in the Sahara (imaged by the Space Shuttle)

37 Ice/tar dunes on Titan

38 Water Channels on Mars

39 Ethane Channels on Titan

40 Impact Cratering Bodies from space hit the ground, making a hole. (the only external process -it comes to the planet from the outside) The size of the hole depends on the energy of the impact. A small, slow-moving, ice-ball makes a small hole. A massive, fast moving, rock makes a large hole.

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42 Imbrium Basin Moon

43 Crater Dating Solar System debris falls onto planets at a regular rate, making craters. The number of holes on a surface is a measure of how long it has been exposed to impacts. Impact craters can be destroyed by the three internal processes (tectonics, volcanism, erosion) Surfaces with few craters have active processes destroying the craters. (called YOUNG surfaces) Surfaces with lots of craters have no active processes & are undisturbed. (OLD surfaces)

44 Which Surface is Older? B A

45 Which World is More Active? (Be able to explain your choice) Earth Moon

46 Planetary Atmospheres

47 Atmospheric Basics Our goals for learning What is an atmosphere? How do you obtain an atmosphere?

48 What is an atmosphere? An atmosphere is a layer of gas that surrounds a world

49 How do you obtain an atmosphere? Gain volatiles by comet impacts outgassing during differentiation Ongoing outgassing by volcanoes

50 Keeping an Atmosphere Atmosphere is kept by the world s gravity and temperatures Low mass (small) worlds = low gravity = little atm. High mass(large) worlds = high gravity = thick atm. Low temperatures = slow gases = more atm. High temperatures =excited gases = atm.loss Gravity and pressure Air pressure depends on how much weight of gas is there ie. The atmospheric thickness.

51 What have we learned? What is an atmosphere? A layer of gas that surrounds a world How do you obtain an atmosphere? comet impacts plus outgassing by differentiation, or volcanoes. How much atmosphere is retained depends on the world s gravity and temperatures

52 Atmospheric Processes 1 Our goals for learning What are the key processes? What creates wind and weather? How does the greenhouse effect warm a planet?

53 Atmospheric Processes Atmospheric circulation (convection) Convection cells move gas from equator to pole and back. Coriolis Effect Gas dragged sideways by the rotation rate of the world. Greenhouse Effect Infrared energy is re-reflected back to the ground by CO2

54 Air Movement Gas molecules move from high density to lower density

55 Atmospheric Pressure Gas pressure depends on both density and temperature. Adding air molecules increases the pressure in a balloon. Heating the air also increases the pressure. (molecules more energetic)

56 Atmospheric Circulation (convection) Heated air rises at equator Maximum Sun warming Cooler air descends at poles

57 Coriolis Effect

58 Coriolis Effect breaks up Global Circulation On Earth the large circulation cell breaks up into 3 smaller ones, moving diagonally Other worlds have more or fewer circulation cells depending on their rotation rate

59 Coriolis Effect Winds blow N or S Venus Winds are diagonal Earth Mars Winds blow W or E Jupiter, Saturn Neptune, Uranus(?)

60 Greenhouse Effect

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62 If there was no greenhouse effect, Earth... A. would be warmer than it is today. B. would have a thicker atmosphere. C. would be colder than freezing. D. would have no protection from ultraviolet radiation Pearson Education, Inc.

63 What have we learned? What creates wind and weather? Atmospheric heating and Coriolis effect. Solar warming creates convection cells. The coriolis effect drags winds sideways and breaks up the cells The faster a planet spins, the more E-W gas movement there is How does the greenhouse effect warm a planet? Atmospheric molecules allow visible sunlight to warm a planet s surface but absorb infrared photons, trapping the heat.