1. © 2009 W.W. Norton Earth Liquid water on its surface Oxygen atmosphere Only planet known to support life 4.6 billion years old 71% covered by H 2 O Oblate spheroid (squished sphere)

2. © 2009 W.W. Norton Compositional Zones Crust – 1% of Earth’s mass – Oceanic crust – Continental crust Moho – Lower boundary of the crust – Named after Mohorovicic

3. © 2009 W.W. Norton Compositional Zones Mantle – Layer under the crust – More dense – 2/3 Earth’s mass Core – Center of the Earth – Composed mainly of Fe & Ni

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5. Structural Zones Lithosphere – Part of mantle and all the crust – Rigid layer Asthenosphere – Below lithosphere – Lots of heat and pressure – Can flow

6. © 2009 W.W. Norton Structural Zones Mesosphere – Layer of solid mantle rock – Between asthenosphere and outer core Core – Outer core – dense liquid – Inner core – dense, rigid solid

7. © 2009 W.W. Norton Magnetosphere Earth’s magnetic field Extends beyond the atmosphere Affects a region of space

8. Magnetic field permeates the space around the Earth. It is symbolized by a bar magnet. Fig. 1.11a,b Magnetic field of a bar magnet. Magnetic field of the Earth. Field flow lines come out of S pole, and go into N pole. Note the error in the arrow directions at S Magnetic field lines.

9. © 2009 W.W. Norton Earth’s magnetosphere (the region inside the magnetic shield). Solar wind interacts with Earth’s magnetic field. Solar wind Distorted magnetic field lines Van Allen belts The solar wind distorts the magnetosphere into a teardrop shape, pointing away from Sun. Earth magnetic field deflects most of the solar wind (like a shield), so that its particles do not reach Earth surface. The Van Allen radiation belts trap charged particles, and protect life on Earth. The belts contain solar wind particles as well as cosmic rays which, because of their fast speed, penetrated the outer weaker part of the Earth magnetic field, which are then trapped by the stronger inner field. Fig. 1.11c Magnetosphere

10. © 2009 W.W. Norton The aurora in the Arctic. Some of the Solar wind particle, which make it through the Van Allen belts, are channelized along the magnetic field lines to their polar regions. These particles then interact with the gases in the upper atmosphere, making them to glow, creating aurorae. Fig. 1.11d

11. © 2009 W.W. Norton Earth, as viewed from space. Earth atmosphere is mostly nitrogen and oxygen, with minor amounts of Ar, CO 2, and other gases. Atm. Density decreases with altitude (we cannot breath freely at 12 km because of sparse O 2 molecules).. Fig. 1.10

12. © 2009 W.W. Norton Gravity Force of attraction between 2 objects Based on mass differences and distance between the objects Weight – force due to gravity (varies) Mass – amount of matter (constant)

13. © 2009 W.W. Norton Systems Group of related objects or components that interact to create a whole Earth systems transfer matter and energy between them Closed system – nothing in or out Open system – Matter & energy can leave or enter system

14. © 2009 W.W. Norton Earth ’ s Four Spheres Makes up Earth systems 1) Atmosphere Blanket of gases that surround Earth 2) Hydrosphere Water portion of Earth 97% salt water 3% Fresh water

15. © 2009 W.W. Norton Earth ’ s Spheres 3) Geosphere Mostly solid part of Earth Crust to core 4) Biosphere All forms of life in the other spheres

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18. Earth ’ s Cycles 1) Nitrogen cycle 2) Carbon cycle 3) Phosphorus cycle 4) Water cycle Evaporation, condensation, precipitation

19. © 2009 W.W. Norton Ecology Ecosystem – Community of organisms and their abiotic environment – Producers, consumers, decomposers Carrying capacity

20. © 2009 W.W. Norton Earth ’ s Energy Budget Internal Sources – Radioactive decay – especially early – Pressure External Sources – Sun Causes motion of air & currents Photosynthesis – Gravitational energy from sun & moon