Overview of Heat-Trapping Gases
Transcript Overview of Heat-Trapping Gases
Overview of Earth’s HeatTrapping Gases
The Earth’s Atmosphere (60 miles thick)
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.
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
Earth’s Atmospheric Composition
2 bonds (1 triple,
trace to 0.00080 2 single
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”.
Greenhouse gas ABSORBANCE (in white)
Effect of Heat-Trapping Gases
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
This Is What Worries Many Scientists
Simplified Example of a Combustion Reaction