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What is the ozone layer?
It is thin, far away, and nearly invisible,
but it is good fortune that an ozone layer surrounds the
Earth.
Add one more atom to an oxygen molecule (O2)
and you create ozone (O3).
A thin band of ozone encircles Earth in the Earth’s
stratosphere, 20–50 km (12–30 miles) above Earth’s
surface. Scientists dub this “good” ozone, thankful
that this layer blocks some dangerous ultraviolet (UV) light
from the Sun.
Without this shield, living things would have
to deal with an increase in UV radiation. From more intense
sunburns to possible skin cancer, UV radiation damages and
destroys cells. There is enough concern about UV radiation
to measure it on a UV index. Based upon the thickness of
the ozone layer, cloud cover, the season, and elevation,
the UV index warns about minimal (0) to maximum (10) risks.
Understanding the UV index helps us avoid unnecessary exposure
to harmful radiation.
Is there really a “hole” in the
ozone layer?
Don’t expect to see a layer of ozone,
much less a hole in the layer. First observed over Antarctica
in 1985, British scientists noticed a reduction in the concentration
of ozone. Since then, the layer has continued to thin. This
thinning was a “red flag” alarm to scientists.
Clearly, human activity was hurting the Earth in ways that
could have drastic long-term effects.
Chlorofluorocarbons (CFC) were among the culprits.
These chemicals are found in aerosol sprays and some fast
food containers. They were used as refrigerants to cool
refrigerators and air-conditioners. When released into the
atmosphere, CFCs gobble up and destroy ozone molecules;
in fact, one free chlorine atom from a CFC molecule can
destroy millions of ozone molecules.
Good news!
The use of CFCs has been banned by some and
reduced by others, notably through the 1987 Montreal Protocol,
an international agreement. Since 2000, the ozone layer
has shown signs of “healing.”
Man is not the only foe responsible for damaging
Earth’s ozone layer. New evidence from NASA and NOAA
satellites show that electrically charged particles from
large solar storms attack a small percentage of this shield.
Unlike man’s impact, this change is temporary, lasting
only weeks to months after the event.
It’s interesting to know that there
is also “bad” ozone.
People pollute the troposphere, the level of the atmosphere
in which we live, through automobile and industry air pollution.
Ozone, one part of this air pollution, is one of the more
dangerous particles in smog. It damages parts of your lungs,
leading to respiratory infections. Young children and the
elderly are most affected by increases in air pollution.
Ground level ozone also harms plants. Increased
levels may damage trees, crops, and forests.
It would be nice if the “bad ozone”
could be used to patch the “good ozone.”
Since it can’t, human beings will simply
need to continue to change their behavior and stop damaging
the Earth’s environment.
Visit the links below for more resources from
NASA:
Ozone,
Orbits, and Atmosphere - To measure the distances
between the layers of Earth's atmosphere and locate the
ozone layer and the orbit of the International Space Station.
Pollution
in the Air - To learn how burning contributes
to air pollution.
When
You're Hot, You're Hot! - To graphically analyze
ozone measurements for the past three decades.
Layers
of the Atmosphere - To use a KWL chart and
a model of the atmosphere to learn about the different atmospheric
layers.
Do-It-Yourself
Ozone Detector - To create an ozone detector
to test for ground-level ozone levels.
Planetary
Geology Educator's Guide - This educator's
guide features lesson plans and activities on the following
topics: introduction to geologic processes, impact cratering
activities, planetary atmospheres, planetary surfaces, and
planetary geologic mapping.
The
Air We Breathe - A picture book designed to
introduce Earth's atmosphere and its importance to life
on Earth. (PDF)
Investigating
the Climate System - A list of various lesson
plans and activies that investigate the Earth's climate.
The major topics covered are: clouds, energy, precipitation,
weather, and winds.
Whose
air is it Anyway? - A middle school level article
on the one thing we all share--air.
Ozone:
Friend and Foe - This feature, written to grade
levels K-4, describes the ozone.
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