1. Solar System Astronomy Earth Lecture 2
Earth’s Interior, Plate tectonics, Climate, Atmosphere, Global warming

2. Overview of Earth’s Interior

3. Interior Temperature Increases with Depth

4. Earth’s Magnetic Field
Current position of N magnetic pole

5. Motion of Magnetic poles
Sir John Ross (1831) first discovered N magnetic pole while exploring the Arctic. He was trapped in the polar ice for 4 years (!) and made magnetic observations to pass the time.
100 km
1000 km
North magnetic pole is now moving N about 15 km/yr
Daily Magnetic pole motion

6. Aurora
Solar wind electrons precipitate into polar regions, ionizing nitrogen and oxygen atoms

7. University of Iowa VIS Auroral Imager Instrument

8. Auroral Imaging movie from Polar VIS Instrument

9. Plate Tectonics

10. Continental Drift
North American plate moves 50 cm per year

11. Continental drift: Historical Maps

12. Movie of Continental Drift
Time (Myr)

13. Alfred Wegener and Continental Drift: Embattled Scientist
Wegener first proposed continental drift theory in It was soundly rejected, and only became accepted after his death
A. Wegener ( )

14. Earthquake zones vs. Tectonic Plates

15. Principle of the Seismograph

16. San Andreas Fault
The San Andreas Fault is a transform fault margin that separates the Pacific plate from the North American plate. Directions of motion are shown by the arrows. Los Angeles, on the Pacific plate, is moving north, while San Francisco is moving south, bringing the two cities closer together at a speed of 5.5 cm/y; they will be adjacent about 10 million years in the future.

17. Locating an earthquake epicenter using seismic waves

18. Seismic Risk Map of U.S.
Note: This map does not indicate frequency of earthquakes

19. Earth’s atmospheric gases
Earth at early epochs had x (15%-30%) CO2 than current levels (0.03%)

20. Transmission of atmosphere versus wavelength
Ozone blocks harmful UV: skin cancers
CO2 blocks IR: global warming
Infrared Visible Ultraviolet

21. UV Protection from Atmospheric Oxygen Isotopes

22. Greenhouse effect

23. Comparison of Greenhouse effect on terrestrial planets

24. Atmospheric carbon dioxide concentration 1950-2000

25. Atmospheric C02 versus CO2 emission from fossil fuels

26. Global land temperature 1860-1997
From the late 1860s to the early 1940s, the annual mean temperature rose about 0.6 degrees C. From the early 1940s to 1965 the temperature declined about 0.2 degrees C and since 1965 the trend has been upward. The overall rise during the century and a quarter of record is ca degrees C. The decade of the 1990’s has been the warmest on record

27. Future Effects of global warming by CO2

28. Predicted global temperature increase for doubling CO2
Northern hemisphere Summer (C)
Northern hemisphere Winter (C)

29. Model of Precipitation Changes caused by doubling CO2 concentration

30. Long-term global temperature variations
Variations in the oxygen-isotope ratio through the Greenland Ice Sheet. The zone of strongly negative values beginning about 70,000 years ago and ending about 10,000 years represents the last glaciation. The pronounced shift in values about 10,000 years ago marks an abrupt change from glacial to interglacial climate at the end of the glaciation.

31. Glaciation Cycles Measured by Oxygen Isotope ratios
Curve of average oxygen-isotope variations during the last 2 million years based on analyses of deep-sea sediment cores. The curve illustrates changing global ice volume during successive glacial-interglacial cycles of the Quaternary Period

32. North America during last glaciation (10,000 BCE)
Des Moines lobe

33. Europe during last glaciation (20000 BCE -10000 BCE)

34. Affect of glaciation on trees species
Simplified pollen diagram prepared from data collected at Rogers Lake, Connecticut. Variations in pollen influx are plotted as a function of time, and show progressive changes in forest composition.

35. Greenland ice core acidity records of Volcanic eruptions
Acidity record from a Greenland ice core showing peaks in sulphuric-acid precipitation attributable to major volcanic eruptions. The largest acid peak dates to , the time of the huge Tambora eruption in the East Indies, which produced "the year without a summer" (1816). The volcanic dust and gases in the stratosphere reduced northern hemisphere temperatures at least 0.7 degrees C.

36. Effects of volcanic eruptions on global temperature
My. Pinatubo eruption June, 1991 (Phillipines)