May 11, 2007
Story Board for Atmosphere Applet
After your zoom in to the atmospheric envelope, first just see atmosphere, with no temperature
profile or layers of atmosphere displayed.
Then the following text in the top right (this wording will need editing, but it’s a start).
1. How does the density of air molecules change with altitude? (Click to show something
like what you see in the right side of the figure below t, which might stay as a narrow box
on the right of the applet if there is enough real estate. If not make it disappear again)
2. What are the regions of the atmosphere? (Click to show troposphere, mesosphere,
thermosphere, ionosphere, labels appear)
3. What determines the boundaries for atmospheric regions? (Click to show words:
“Atmospheric regions are defined by the change in temperature with altitude)
4. Does it get colder or warmer as altitude increases? (click to show the temperature profile,
and then the following wording appears. The relationship between temperature and
increasing altitude changes in different regions of the atmosphere. Regions are defined by
a reversal in the temperature profile. In the troposphere, temperature decreases with
altitude. This is reversed in the mesosphere. Different interactions of electromagnetic
radiation with atmospheric molecules is responsible)
5. Troposphere – Suppose molecules of a CFC refrigerant, CF2Cl2, are released from a
landfill. What’s the most important interaction they would have with electromagnetic
radiation in the troposphere? (click to show the animation and words: infrared radiation
from the sun and the surface of the earth are absorbed by CF2Cl2 and other greenhouse
gases, causing bonds to stretch and bond angles to bend).
6. Troposphere – How does this absorption of infrared light by greenhouse gases cause
tropospheric warming? (click to show the CO2 animation and the words: a primary
mechanism for warming is collisional de-excitation. N2 and O2 molecules in the
troposphere collide with vibrationally excited greenhouse gases, increasing their kinetic
energy. Since the density of air molecules is higher near the surface of the earth, it
becomes warmer there.)
7. Stratosphere – Since CFCs like CF2Cl2 undergo no chemical reactions in the
troposphere, the only mechanism for removal is to cross into the stratosphere. What’s the
most important interaction they would have with electromagnetic radiation in the
stratosphere? (click to show the animation and words: Ultraviolet radiation from the sun
is absorbed by CF2Cl2. These photons are sufficiently energetic to cause dissociation of a
C-Cl bond, forming Cl free radicals which can initiate chain reactions that destroy
stratospheric ozone).
8. Where is most of the atmospheric ozone found? (click to show the profile from
Chemistry in Context and the words: Ground level ozone is formed mostly as a result of
photochemical reactions involving hydrocarbons and nitrogen oxides from auto
emissions and other human activity. Stratospheric ozone is found in highest
concentration between 15-35 km (check) and is formed as a result of ultraviolet energy
from the sun interacting with molecular oxygen. Show the two reactions of the Chapman
cycle – redraw something like
)
References:
http://imagine.gsfc.nasa.gov/docs/science/know_l1/emspectrum.html - on electromagnetic
spectrum
http://www.atmosphere.mpg.de/enid/1__Oxidants___Observation/_observation_spectroscopy_l6.html
Chapman cycle is from Crutzen’s Nobel Prize speech on the Nobel website.