STUDY GUIDES

Second Midterm Study Guide

First Midterm Monday, March 3, 2 p.m., Stv. 3036

UNDER CONSTRUCTION, NOT COMPLETELY EDITED YET
The first midterm will consist of ten multiple choice questions (1 pt each), ten short answer questions (3 pts each) and one short essay (10 pts). The short answer questions should be answered briefly, with a few words or phrases, and possibly a sketch. You will have several choices of topic for the short essay question, and will answer it in one or two short paragraphs for a total of no more than one page of text. You may also want to use a sketch or diagram to illustrate your essay. This midterm will cover Ruddiman, Chapters 1-3.

The following topics and concepts will be covered on the first midterm.

How to study: go over your notes carefully, review illustrations in the text, re-read portions of the text that are not clear, ask questions of your fellow students and Prof Freidel, via email or in class.

Climate -- basic processes

See Fig. 1-5, page 9, Ruddiman, be able to discuss
Climate forcing -- tectonic, orbital variations, solar radiation variations, anthropogenic
Response to forcing (see Table 1.1, page 12), fast, slow
Feedbacks: Positive (reinforces and amplifies change); Negative (suppresses change, reduces response)
Uniformitarianism -- Present is key to the past; past is the key to the future

Solar radiation as driving force for general atmospheric circulation
Energy balance of earth (See Fig. 2-3, page 20, Ruddiman)
incoming shortwave (solar, insolation)
portions reflected, scattered, absorbed (by what?)
outgoing long wave (heat) radiation
portions absorbed and reradiated (by what?)

Earth’s albedo, albedo of different surfaces (high or low) (Table 2-1, p. 23)
Albedo-temperature feedback, positive when ice forming, positive when ice melting

Electromagnetic spectrum
compare earth and solar energy outputs
radiation laws re wavelength, energy emitted, energy intercepted with distance

Latitudinal differences in energy --
Differences in solar angle (angle of incidence)
low latitudes - high energy input -- surplus
high latitudes - low energy input -- deficit
Energy transported from surplus to deficit areas by ocean currents, winds,
Latent heat storage and release during evaporation and condensation

Controls on climate distribution from place to place
General atmospheric circulation
continental masses, distribution and relief
continentality (Fig. 2-9, p. 26)
ocean circulation, shape and size of ocean basins
thermohaline circulation (fig. 2-24, p. 40)
cold water upwelling
elevation and topography
surface cover, vegetation

Hydrologic cycle (See box, p. 27)

Greenhouse effect
Gasses in the atmosphere that absorb outgoing longwave radiation
CO 2, H 2O, CH 4, N­ 2O.
About 50% of Incoming solar radiation passes through atmosphere without absorption; about 20% is absorbed by clouds and atmosphere
Total of about 70% of insolation heats surface and atmosphere; 30% is earth's albedo
Outgoing Longwave energy (heat) is recycled by clouds, absorbing gases,
reradiated back toward earth’s surface and radiated out to space

Carbon cycle, sources of CO2 storage and release

Evidence of past climate
Notes and images from ppt on Climate Archives
Proxy indicators -- (be able to define term)
Dendroclimatology -- tree rings
Fossil vegetation --
pollen -- how collected, interpreted
plant assemblages
plant macrofossils -- especially in
packrat middens -- where found, how preserved, etc.
lake levels of closed-basin lakes, water balance proportional to climate change
lake varves
ice cores
marine cores, plankton, forams, radiolarian, diatoms
Stratigraphic layers -- relative age
Stratigraphic markers -- tephras (volcanic ash)

Dating methods
Numerical dating methods--
Instrumental, back to a couple of hundred years, poorly distributed globally
Also annual layers: tree rings (dendrochronology), sediment varves, ice layers, corals
Radiometric -- based on breakdown of isotopes, radioactive decay
Halflife -- what does this mean? Useful dating period for each isotope
Types of material dated for each isotope -- e.g. organics by C-14
Radiocarbon (C-14 into N-14)
Uranium series; Potassium-Argon;
Cosmogenic isotopes -- C-14, also Cl-36 in rocks
Relative and Correlative Dating methods--
Tephrachronology -- id tephras by oxides of elements
Paleomagnetism -- correlate variations in earth's magnetic field over time, place to place

Climate Models
Physical climate models -- 1-D, 2-D, 3-D Global Circulation Models (GCMs)
Purposes, resolution, time periods

History of climate fluctuations through time
Range of time scales (see Figure1.2 and 1.3 pages 5-6, Ruddiman)
Do not memorize dates, but focus on patterns of climate variations through time
e.g. major glaciations lasting several million years every several hundred million year periods (not cyclic)
Know names, terms, geologic time periods:
Quaternary (last ~1.6 my),
Pleistocene (ice age, 1.6 my-10,000 C-14 yr BP),
Wisconsinan glaciation (~80,000-10,000 yrs BP),
Eemian, last interglacial, (~125,000 yrs BP)
Holocene (last 10 ky),

Possible Causes of past climate fluctuations -- on range of time scales, long term to short term
Continental drift (distribution of continents at high or low latitudes, scattered or concentrated)
Mountain building (orographic precipitation, change in atmospheric circulation, weathering)
Weathering, chemical (See Fig. 3-21, p. 70)
Changes in ocean circulation patterns
Changes in CO2 in atmosphere and oceans
Orbital parameters (briefly)--
eccentricity of orbit-- circular to elliptical -- ~100,000 year cycle
tilt of earth's axis -- ~21.5 to 24.5 degrees -- 41,000 year cycle
Precession of equinoxes: timing of perihelion and aphelion -- ~23,000 yr cycle
Changes in solar output -- sun spots, or lack of sun spots
random: meteor strikes, volcanic eruptions (short term)

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