9. Mars Atmosphere: mass <1% earth’s GH Gases: >80% CO 2 Sfc. Temp.: -47  C GH Effect: 10  C FAR TOO COLD! Other planets also have Greenhouse Effects, but these are unsuitable for life Earth GH Gases: ~0.04% CO 2 ~ 1% H2O Sfc. Temp.: 15  C GH Effect: 33  C NOT BAD! Venus Atmosphere: mass 90x earth’s GH Gases: >90% CO 2 Sfc. Temp.: 477  C GH Effect: 523  C FAR TOO HOT! Sun

10. The “Greenhouse Effect” The Earth’s surface thus receives energy from two sources: the sun & the atmosphere –As a result the Earth’s surface is ~33  C warmer than it would be without an atmosphere Greenhouse gases are transparent to shortwave but absorb longwave radiation –Thus the atmosphere stores energy

11. Electromagnetic Spectrum incomingoutgoing