CLIMATE

1. CLIMATE

2. After the surface of the earth cooled and surface crust (lithosphere) formed, the planet surface took on something of the “look” it has today – land, air, oceans (lithosphere, atmosphere, hydrosphere)

3. The temperature at the ______ of the earth is determined, not by geology of the core but primarily by energy coming from outside – the _____.

4. NASA

5. What is energy? The capacity to do work (move mass) and transfer heat Two main forms: 1. ________ – a mass moving 2. _________ – “stored” in a structure, molecule, nucleus - able to become kinetic under right conditions

6. Nuclear fusion Reaction conditions Products Fuel Helium-4 nucleus Proton Neutron Hydrogen-2 (deuterium nucleus) 100 million °C Energy Hydrogen-3 (tritium nucleus) Neutron Where does the sun get it’s energy? Nuclear fusion Atoms of hydrogen fuse to form __________ – releases large amounts of energy 9-18/10-19 Requires extremely high pressure & temperature conditions, such as exist in the sun. Fusion reactions further _______ these temperatures.

7. How does the sun supply energy to the earth? The sun is a “hot body”. Hot bodies emit ___________ waves (EM), as a function of their temperature.

8. What are electromagnetic waves? Light. Physicists tell us that light has both ____ and particle properties. The particles are called “photons”, the wavelength measures their energy level. The energy of light is determined by ___________ hc E = energy E = ------ h = Planck’s constant  c = speed of light  = wavelength

9. There is a broad spectrum of wavelengths and energies Shorter waves = _______ energy

10. Visible light is a small segment of the electromagnetic spectrum

11. The sun emits electromagnetic waves as a function of its temperature. Its heat results from nuclear fusion (H to He) Peak (intensity) wavelength of a radiating body (Wein’s law) Max  = 2.88 x 106 / T (oK) T = temp Sun temperature 5750 oK Sun’s max  = (2.88 x 106)/5750 = 500 nm (__________) Interestingly, at planet formation, sun 25% ________; max  = 670nm – orange Stars heat up as they age (why?)

12. Total light energy is distributed around this peak wavelength 2-6

13. Much of the energy hitting the earth is in the ______ spectrum Is this just a lucky coincidence?

14. The density (#photons/m2) _________ with distance from the sun The energy density intercepted by the earth is determined by the distance to the sun. “Solar _________” = 2 cal/cm2/min 1 cal/cm2/min reaches surface Varies through the year – orbit an _________.

15. The total energy intercepted by the earth a function of area of the “profile”. (earth radius = 6378km) Solar constant x area = 2.495 x 1018 cal/min This energy input creates a surface temperature, a “dynamic equilibrium” – a balance of inputs and outputs 2-10

16. What is a dynamic equilibrium? “Equilibrium” describes an entity that appears _____________ over time, a “steady state”. For example, a tub of water half full. There are at least two ways that tub could stay half full. 1. Turn off the tap - it sits there unchanging. 2. Leave the tap on, but open the drain. #2 is a “dynamic equilibrium”

17. Obviously, a key relationship for a dynamic equilibrium is ________ = __________ What happens to an equilibrium if you increase inputs? Does the water level go up, down, stay the same? What did you assume to decide on your answer?

18. We can easily imagine at least three ways to get a dynamic equilibrium in our bathtub 1. ________ output, ________ input – adjust input to match output. Total amount in tub is irrelevant. (could also have fixed input, match output) 2. Output __________ as input increases. a. tub is fixed size, overflow = input, tub full. b. output increases as amount in tub increases, output eventually matches input What kind of dynamic equilibrium is earth surface temperature?

19. Surface temperature is a balance of solar inputs, reflectance, _________ and re-radiation (into space). Re-radiation is also EM waves, at _____ wavelength If no re-radiation, no heat loss, earth ____________. As the earth heats up, it re-radiates more (output increases) Type 2b dynamic equilibrium Higher input, _________ equilibrium temperature.

20. If sun was cooler in past, earth was __________, yes? Maybe, but this ignores the “greenhouse effect” Components of atmosphere absorb outgoing wavelengths, re-radiate back to _____, increase heat before leaving at lower energy.

21. Depends on composition of the atmosphere. Carbon dioxide, ________, __________, and nitrous oxide are strong “greenhouse gases”. Early earth atmosphere was _____ in these, so may have been as warm as or warmer than today (est. 23oC).

22. Question: what would be an equivalent of the greenhouse effect in the bathtub analogy?

23. Estimates of global temperature indicate lots of changes during the history of the planet. Barry Saltzman, Dynamical Paleoclimatology: Generalized Theory of Global Climate Change, Academic Press, New York, 2002, fig. 1-3.

24. Including “_________” that lasted many thousands of years NOAA Much of the earth was covered with ice packs miles deep, that altered the landscape and created lakes and rivers when they melted.

25. The most recent glacial period began about 70,000 years ago, and ended about _________ years ago.

26. These changes in ice pack directly affect the amount of liquid water and therefore ocean levels.

27. 12-17/12-16 Greenhouse gas composition is one factor affecting this temperature variation 12-16/12-15

28. 12-17/12-16

29. A B A B Dynamical systems like surface temperature can be difficult to understand and predict because of the interconnectedness of the component processes. These connections create feedback loops, or causal cycles rather than simple causal chains like A affects B affects C. For example, two simple feedbacks + 1. ________ feedback – increase in A increases B, which decreases A. “homeostatic”, “stable” _ 2. _________ feedback – increase in A increases B, which further increases A. “Blowup” or “collapse”. + +

30. In earth temperature regulation, we have already seen an example of each 1. Re-radiation: _________ feedback. Increasing solar input (heating) results in increased radiation to space (cooling) + Earth temp. Re-radiation _ 2. Water Vapor: __________ feedback. Increased temperature increases evaporation, increased water vapor in atmosphere increases greenhouse effect. + Earth temp. Water vapor +

31. But also, increased water vapor in the atmosphere tends to increase cloud cover, which increases ________ and thereby decreases earth temperature + What would you call this?? Earth temp. Water vapor + + _ In the bathtub analogy, what is equivalent to cloud cover? Cloud cover Predicting cloud cover is an important source of _________ in climate modeling.

32. Solar energy density is not even across the earth or through the year – climate varies from place to place. _____ in winter, _____ at poles. Opposite seasons in the northern and southern hemispheres

33. Three basic ways heat is transferred: 1. Convection – movement of heated fluid due to density 2. Conduction – direct contact – molecular collisions 3. Radiation – EM waves from hot body

34. Wind and ocean currents move heat around _________ cells – warm moist air rises at equator, cools, rains; high dry air moves toward poles, cools and sinks. 12-3 Six “Hadley cells” in earth redistribute heat and moisture

35. Wind and ocean currents move heat around _____ winds form due to earth’s rotation – faster at equator than at poles Which way does the earth turn?

36. Wind and ocean currents move heat around Similar forces generate ocean currents: differences in temperature, wind, topography, _______, earth’s rotation These currents can alter ________ on land in coastal areas http://earth.usc.edu/~stott/Catalina/Oceans.html

37. Cold, salty water in the North Atlantic sinks and flows south into the Pacific, eventually warms, rises and returns.

38. Topography can also alter climate 1. High altitude air is ________ – lower pressure 2. The “rain shadow effect” – ______ on the “lee” side

39. Weather – large air masses generally moving and interacting – local climate conditions frequently change Fronts – where different air masses contact, energy is transferred. ______ front – moving warm air mass contacts a cold mass, it rises up, widespread clouds. ______ front – moving cold mass drives under a warm air mass, sudden cooling, strong winds and rain.

40. Tornadoes High energy concentration can result in special storms with spiraling high velocity winds Hurricanes (Typhoons)

41. ___________ cycle _____ driven evaporation of water into air begins a cycle as the warm moist air rises, condenses to clouds and rain, which returns directly to surface water (lakes, oceans) via rivers and underground (ground water flow), and so on. 2-19/2-25

42. Energy flow and material cycles The water cycle is an example of a general natural pattern on earth the linkage of the flow of energy and cycling of materials EM (Space) Water vapor Energy flows Water cycles Liquid Water EM (Solar)

43. 12-2 These multiple forces drive variation in climate across the world

44. Conclusions earth a dynamic process, has history geologically active – rock cycle temperature a balance of factors solar energy drives climate patterns water cycles through its states flows of energy and cycles of materials interaction of geological and solar energy NOAA