Energy Transfer

1
Energy Transfer

• Conduction, Convection, Radiation
• Global Warming

2
Thermal Conduction

• Materials in _________ ________
• _____________ energy transferred by atoms and
  free electrons
• Metals are _________ thermal conductors
• Gases are _______ thermal conductors
• ____ of energy transfer depends on material

L
Fig. 11.5, p. 366
3
Home Insulation

• In U.S. units are BTUs, feet, ?F, hours
• Compound slabs use __ ______
• Thin layer of _________ air at surfaces also
  insulates
• Rate of heat transfer given by

4
Convection

• Transfer of energy by ____________ of substance
• Natural convection movement from _______
  differences
• Forced convection movement by ____ or _____

Fig. 11.10, p. 371
5
Radiation

• ______________ waves from thermal vibration of
  molecules carry energy
• Characterized by
• objects ___________, e
• Stefan-Boltzmann constant, ?
• Surface _______, A
• Can also _____ radiation

6
Global Warming and Greenhouse Effect

• Some gases transmit _______ light, _______
  infrared light (like glass of greenhouse)
• CO2, CH4, N2O, SO2
• Leads to ______ surface temperature (properly
  called the atmospheric effect)
• Too little ? ________ changes in temp. (Mars)
• Too much ? ________ high temp. (Venus)

Seeds, Foundations of Astronomy, p. 490
7
Four predictions of Earths CO2 History
Predictions based on marine sediments (1)
deuterium, dust, deep ocean carbonate
dissolution, calculated insolation (2)
insolation only model of ice formation (3) and
deuterium levels (4)
Wolff, E., et al. (2005), Modeling past
atmospheric CO2 results of a challenge, EOS
86(38), pp. 341, 345
8
CO2 Measured from ice core samples from
Antarctica
Minima are _______ periods maxima are
___________ periods
Wolff, E., et al. (2005), Modeling past
atmospheric CO2 results of a challenge, EOS
86(38), pp. 341, 345
9
CO2 measured at Mauna Loa Observatory along with
fossil fuel emissions
Deforestation
Graedel, T.E. and P.J. Crutzen (1993),
Atmospheric Change An Earth System Perspective,
p. 255, W.H. Freeman and Company, New York.
10
Source http//www.esrl.noaa.gov/gmd/ccgg/trends