Overview of Earth’s HeatTrapping Gases
LESSON 4
Electromagnetic Spectrum
http://9-4fordham.wikispaces.com/Electro+Magnetic+Spectrum+and+light
Earth’s Magnetosphere
The Earth’s Atmosphere (60 miles thick)
http://www.grc.nasa.gov/WWW/k-12/airplane/atmosphere.html
Sun’s Emission Spectrum able to penetrate Earth’s atmosphere
The blue line indicates the approximate intensity of radiation that penetrates Earth's atmosphere at wavelengths from
the ultraviolet (UV) through the visible to the infrared. Light at low UVC wavelengths is completely absorbed by the
atmospheric ozone layer, so organisms on Earth have developed no tolerance to it.
http://www.nature.com/nature/journal/v441/n7091/fig_tab/441299a_F1.html
What does this penetrating energy do to Earth?
Being light, infrared travels
through space at the speed of
light. Matter is not space and
the Earth’s atmosphere is
obviously matter. Heat is a
property of matter. The rate
of transmission is slowed as
this energy enters the
atmosphere. Work is thereby
done; so heat is created.
Some atmospheric molecules
are more sensitive to this
energy than others based on
their molecular shape and
bonds.
http://www.windows2universe.org/physical_science/chemistry/molecules_vibrate.html
Earth’s atmosphere
http://www.agci.org/classroom/atmosphere/index.php
Earth’s Atmospheric Composition
CONSTITUENT CHEMICAL
SYMBOL
99%
BONDING
Nitrogen
N2
78.084
1 triple
Oxygen
O2
20.947
1 double
Argon
Ar
0.934
-
CO2
0.035
2 double
Carbon Dioxide
Neon
Ne
0.00182
-
Helium
He
0.00052
-
CH4
0.00017
4 single
Methane
1%
MOLE %
Krypton
Kr
0.00011
-
Hydrogen
H2
0.00005
1 single
0.00003
2 bonds (1 triple,
1 single)
-
Nitrous Oxide
N2O
Xenon
Xe
0.00001
Ozone
O3
trace to 0.00080 2 single
http://www.globalchange.umich.edu/globalchange1/current/lectures/Perry_Samson_lectures/evolution_atm/index.html
What is a “Heat-Trapping Gas”?
Objects that absorb all radiation incident
upon them are called "blackbody"
absorbers. The earth is close to being a
black body absorber. Gases, on the other
hand, are selective in their absorption
characteristics. While many gases do not
absorb radiation at all some selectively
absorb only at certain wavelengths of
energy. Those gases that are "selective
absorbers" of solar energy are the gases
we know as “heat-trapping gases”.
http://www.globalchange.umich.edu/globalchange1/current/lectures/Perry_Samson_lectures/evolution_atm/index.html
2500 nm
3330 nm
5000 nm
10000 nm
1000000 nm
http://www.elmhurst.edu/~chm/vchembook/images/irgreengas.JPEG
http://www.elmhurst.edu/~chm/vchembook/images/irwater.JPEG
http://www.elmhurst.edu/~chm/vchembook/images/irmethane.JPEG
http://www.elmhurst.edu/~chm/vchembook/images/irN2O.JPEG
Greenhouse gas ABSORBANCE (in white)
http://en.wikipedia.org/wiki/File:Atmospheric.transmittance.IR.jpg
Effect of Heat-Trapping Gases
http://mrsdlovesscience.com/greenhouse/greenhouse.htm
l
CO2 levels (parts per million) over the past 10,000 years. Blue line from
Taylor Dome ice cores (NOAA). Green line from Law Dome ice core
(CDIAC). Red line from direct measurements at Mauna Loa, Hawaii
(NOAA).
This Is What Worries Many Scientists
0
http://www.realclimate.org/index.php/archives/2004/12/temperaturevariations-in-past-centuries-and-the-so-called-hockey-stick/
Simplified Example of a Combustion Reaction