Atmospheric Chemistry and Dynamics

Junior/Senior High School Education

To fulfill the needs of all different levels of students, we have included a separate section
just for the upper level. Here students will find learning materials to help them with either their
class assignments, or their own personal undertakings. No matter the reason for viewing this section,
we will provide the information needed. As always, if there are questions regarding material on this
site, you can "Ask A Scientist" and a response will be sent out promptly. We wish you luck in your
future science endeavors!

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Stratospheric Ozone Chemistry

One cannot understand the functioning of our atmosphere without having a good understanding of the stratospheric
processes involved. Stratospheric ozone is the beneficial ozone, the ozone that filters out most of the uv-b radiation hitting
the surface of Earth. However, introduction of chlorofluorocarbons into the atmosphere from factories, aerosol cans, and
refrigerants has had a pronounced effect on the stratospheric ozone molecules.

When a cholorfluorocarbon comes in contact with ultraviolet radiation, a chemical reaction takes place and the chlorine atom
breaks apart from the rest of the molecule. This chlorine will eventually attach itself to an ozone molecule(O3) and break
off one of its oxygen atoms. The ozone molecule has then turned into one oxygen molecule and one oxygen atom. In time,
the free-floating oxygen atom then bonds to another free floating oxygen to form an oxygen molecule. This process has
shown how our protective ozone layer is slowly being converted into non-protective oxygen. Yet there is more... Polar
stratospheric clouds are high altitude cirrus clouds and they too contribute to the destruction of ozone. These clouds,
because of their icy nature, serve as catalysts for converting the benign forms of chlorine into ozone-destroying forms.
Scientists are studying the effects of these clouds in the Arctic and Antarctic regions annually. Visit the links below for more
information on stratospheric chemistry.

Tropospheric Ozone Chemistry

In the troposphere, ozone is the man-made ozone existing in the troposphere, the layer nearest the surface. This type of
ozone is strange in that it is both harmful to us AND beneficial. Tropospheric ozone levels have increased over time
with the vehicle traffic and industrialization and, when breathed, this ozone can have negative effects on our health.
Immediate symptoms such as coughing, wheezing, gasping and chest pains are all signs of increased ozone levels. Later
on in life however, one might experience loss of lung capacity and lung cancer. As mentioned before though, tropospheric
ozone can be beneficial as well.

Tropospheric ozone is known to be a forerunner of the hydroxyl radical. This hydroxyl radical is unique as it has an
unpaired electron in its outer electronic orbit. Since the electron is by itself, it searches to join up with others, forming a
chemical bond. The reaction that takes place is important because the hydroxyl radical bonds with compounds such as
hydrocarbons and carbon monoxide which can poison us in large numbers. This has shown how ozone can be both
beneficial and damaging to us. More information can be found on tropospheric ozone by using the following links.

Aerosols and Clouds in Atmosphere

Aerosols are the miniscule particles consisting of dust, ash, exhaust, etc.. Motor vehicle emissions, wildfires, and volcanoes are
just a few examples of how aerosols are introduced into the atmosphere. While these particles are floating about the atmosphere,
they are also reflecting incoming radiation from the Sun. Because there is less uv radiation reaching the surface, the net effect can
be cooling.

We can also discuss this while talking about the effects of clouds on climate. Cloud patterns and effects are quite complex
because they affect the climate and yet are affected by climate at the same time. They affect the climate by reflecting or
absorbing uv radiation. Low-lying, dense cumulus clouds tend to reflect a majority of the sunlight away from the surface,
causing a cooling effect. However, the high altitude cirrus clouds have absorptive properties and tend to absorb most
of the uv radiation. This traps the energy in the atmosphere and creates a warmer overall temperature. After reading through
these findings, one might assume these processes cancel eachother, leading to zero net change. Some studies have shown
however, that the reflective properties of cumulus clouds are greater than the absorptive properties of the cirrus clouds. This
creates a net cooling effect. More information can be found from the following links.

Greenhouse Gases and Global Warming

Since the beginning of life, Earth has provided us with a natural greenhouse. This greenhouse effect has increased the net
surface temperature on Earth, making it sufficient for life. To explain the greenhouse effect though, one must
first understand the idea of greenhouse gases. These gases consist of carbon dioxide, water vapor, methane, and
others, that float freely throughout our atmosphere. When uv radiation enters the atmosphere and reflects off the Earth's
surface, it is then absorbed by the gases, leading to an increased temperature. In fact, almost ninety percent of all sunlight
is absorbed by the gases at work. Without this process, Earth's temperature would be approximately 40-50 degrees cooler.
We can see how vital the greenhouse effect is to our existence!

When the phrase "Global Warming" is mentioned, it is often associated with other negative connotations. This is because
global warming could have severe effects on Earth's life if it is to keep up. Humans may be to blame for this occurrence.
The over-industrialization, the increased number of motor vehicles, and the introduction of chlorofluorocarbons into
the atmosphere are all contributors to global warming. As more and more of these gases are released into the air, more and more
uv radiation is absorbed, which in turn, leads to warmer and warmer temperatures. You can see how this can be a concern
in the future. We have included more information for you below to better your understanding of this topic.

We've included here a diagram of the Earth's atmospheric layers. Hopefully you can get a better understanding
of where all the processes that you read about earlier are taking place.

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Web Creator: Stewart McIlvena

Last modified on: April 2, 2003