012208 Lecture 1 - The Water Planet Yair Rosenthal Lecture...

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The Water Planet Yair Rosenthal Lecture 1: January 22, 2008 Slide 1 Earth has three features: 1. Plate tectonics - earth itself is an active system that changes, not dormant (earth- quakes, volcanoes) 2. Liquid water - only planet with water in liquid form, which enables life 3. Life - The occurrence of, and interactions among these properties make the earth a unique planet. - For example: life had a major impact on the earth especially the composition of the at- mosphere, which in turn influenced the evolution of life. - Earth’s atmosphere has 70% nitrogen, 21% oxygen and 0.000003% CO2 - why so much oxygen? photosynthesis, using sunlight, CO2, and water - anaerobic bacteria- do not need oxygen - Mars has 95% CO2, no oxygen Slide 2 - Integrated system=> Earth system science: interactions are not unidirectional and each system affect the other - Atmosphere - Biosphere - Hydrosphere - Geosphere Slide 3 Scientific Method 1. Observations: understanding something 2. Hypothesis: working plan that needs to be tested a. definition : 3. Test of hypothesis--> theory a. cannot prove hypothesis, but can disprove them using negative examples b. build confidence by continuously providing tests not disproving it, so you accept 4. Validate theories --> natural law a. definition : 5. Continual re-examination: finding evidence in support of a theory or disprove it Example: The discovery of the ozone hole 1974- experiments with CFCs--> Theory - found that CFCs can affect ozone layer in the atmosphere which can lead to ozone de- pletion 1985- first observations of the Antarctic hole
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- first observed System definitions Isolated system: no exchange of energy or matter; inside a vacuum Closed system: can exchange energy (radiation from the sun) but not matter
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012208 Lecture 1 - The Water Planet Yair Rosenthal Lecture...

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