The Greenhouse

Effect

Too much of a good thing?

• Light from the sun is composed of many frequencies

Different light frequencies carry different levels of energy

Greenhouse Gases absorb IR frequency radiation

• Radiation energy can increase vibration between bonded molecules

• Different molecules will absorb and re-emit different energy levels of light waves as heat

• Greenhouse gasses are gasses that absorb IR energy radiation

Which gasses are greenhouse gasses?• Nitrogen    78.1%      • Oxygen     20.9% • Argon          0.9%    • Neon           0.002%  • Helium       0.0005%     • Krypton      0.0001%    • Hydrogen   0.00005% • Water vapor     0 to 4%     • Carbon Dioxide  0.035%     • Methane         0.0002%        • Ozone           0.000004% Percentages indicate levels of concentration in Earths atmosphere

What happens when sunlight reaches the Earth?

• Earth absorbs ultraviolet (UV), visible, and some infrared (IR) radiation from the sun. This heats the earth.

• The earth reflects most IR radiation back towards space and . This process cools the earth.

Absorbtion and Reflection by the Earths Surface

Atmospheric gasses can absorb IR radiation on its way in

Atmospheric gasses can absorb IR radiation on its way out

Why is absorbtion of IR a problem?

• If an atmospheric gas can absorb radiation energy it will release that energy as heat energy back into the atmosphere.

• This results in a warmer overall atmospheric temperature.

What if there was no greenhouse effect?

• The earth would be too cold to sustain life.

• Greenhouse gases are required to keep the earth’s temperature above freezing.

Water vapor

• Water vapor is the gas most responsible for the greenhouse effect.

• Human appear to have little influence over its impact on a global scale.

• It’s levels are regulated by rain/snow.

Carbon Dioxide• Cycles normally through photosynthesis,

cellular respiration, and volcanic activity.

• Humans affect carbon dioxide levels in three ways.

– Burning fossil fuels– Burning vegetation– Deforestation

• What is the impact of each?

Carbon Dioxide today

Does one cause the other?

• More and more evidence says yes, but there is not 100% agreement that the increase in greenhouse gases is causing climate change.

• Unfortunately, the evidence is getting stronger that it does.

Effects of Climate Change

• More extreme weather due do more trapped energy

• Increased sea levels due to loss of ice caps.

• Changes in amount of farmable land

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