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Atmosphere: Earth's Blanket
Transcript of Atmosphere: Earth's Blanket
Mostly made up of nitrogen and oxygen
Consists of 5 layers
Troposphere... the "weather" layer
Stratosphere... warmer; contains greenhouse gases and ozone
Mesosphere... coldest layer; most meteors burn up in this layer
Thermosphere... warmest layer
Exosphere... thinnest layer; contains unstable gases
The Greenhouse Effect
Radiation from the Sun enters the Earth's atmosphere.
This sunlight is partially absorbed by plants, and the rest is reflected back towards space.
Greenhouse gases (carbon dioxide, nitrous oxide, methane) in our atmosphere trap this reflected radiation and do not allow it to escape.
This trapped radiation heats up the atmosphere around Earth.
Without these greenhouse gases, the Earth would be too cold for life.
The greenhouse effect is a natural process and is NECESSARY for life!
The Greenhouse Effect
We depend on greenhouse gases to keep our planet warm enough to live on.
Greenhouse gases occur naturally within our atmosphere.
However, we are increasing these gases by burning fossil fuels and cutting down trees.
The naturally occurring layer of greenhouse gases is getting thicker, increasing the "greenhouse effect".
The Earth's temperature has increased by 0.5˚C over the past 100 years.
It could increase by 1˚C over the next 100 years, doubling its rate of increase!
This could lead to polar ice caps melting, animals becoming extinct because they cannot adapt quickly enough, and water levels around the globe increasing to devastating levels.
The Ozone Layer
Ozone (3 oxygen atoms) forms a layer of gas in the Earth's stratosphere, and protects us from the Sun's harmful ultraviolet rays.
In the 1980s, scientists discovered a hole in our ozone layer above Antarctica.
Certain chemicals that we have used in the past have slowly destroyed these ozone molecules over time, causing our ozone layer to thin out.
Chlorofluorocarbons (CFCs) and other ozone depleting toxins could be found in items such as aerosol sprays, refrigerators and fire extinguishers.
Countries around the world have agreed to stop using and producing these chemicals, but it takes 2-5 years for CFCs to reach the ozone layer, and it takes much longer for ozone gas to regenerate.
What's on your mind?
Now that you have some understanding of how the Earth's atmosphere can be both helpful and harmful, what questions do you have? Bring at least one question to class tomorrow, so that we can discover the answer together!
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