Greenhouse Effect Transparent glass allows visible light to enterWarms the interior as it is absorbed Covering prevents the heat from leaving Reflects the energy back inside and prevents winds from carrying it away.

Greenhouse Effect

Electromagnetic Spectrumincoming outgoing

What is the greenhouse effect?

• Earth absorbs incoming solar radiation (all wave lengths)

• Earth emits long wave infrared radiation

• Infrared radiation is absorbed by greenhouse gases

What the gases do

Greenhouse gases

•transparent to short wave but absorb long wave radiation •atmosphere stores energy •Earth’s surface is ~33C warmer

Greenhouse Gases• Water Vapor (H2))

• Carbon Dioxide (CO2)

• Methane (CH4)

• Nitrogen Oxide (N2O)

• Chlorofluorocarbons (CFCs)

Amounts of greenhouse gases

Mars Atmosphere: mass <1% earth’sGH Gases: >80% CO2

Sfc. Temp.: -47C GH Effect: 10C

The Goldilocks Principle

EarthGH Gases: ~0.04% CO2

~ 1% H2OSfc. Temp.: 15C GH Effect: 33C

VenusAtmosphere: mass 90x earth’sGH Gases: >90% CO2

Sfc. Temp.: 477C GH Effect: 523C

Sun

FAR TOO HOT!

Just Right!!!

FAR TOO COLD!

Summary

Explain why the greenhouse Effect is essential to life on earth as we know it.

Enhanced Effect

Data showing the increasing concentration of Greenhouse Gases:

•CO2 is steadily increasing at the rate of about 1 ppm per year

Methane (CH4) • CH4 is only recently been measured.

Rate of increase is about 10 ppb per year.

• However, since 1 CH4 molecule is worth 25 CO2 molecules, the equivalent growth rate in terms of CO2 is 2.5 ppm. Thus methane will eventually be the dominant enhanced greenhouse gas in our atmosphere.

Conclusion

Why should we be concerned about an increase in greenhouse gases in the atmosphere?

Impact Presentations tomorrow!