Earth’s Atmosphere

Evolution – Additional references– Evolution of the atmosphere (Walker, 1975)

– Chemistry of Atmospheres (Wayne, 1991)

– Chemistry of the Natural Atmosphere (Warneck, 2000)

– Kump, Nature, 2008

– Falkowski, Science, 2005

– Arrhenius law

• Atmospheric fraction of CO2

• Temperature structure– Manabe and Wetherald, JAS, 1967

– Manabe and Stickler, JAS, 1964

• Atmospheric radiation

Wayne, 1991

Warneck, 2000

Banded iron formations

Red beds

Mass dependent fractionation

Mass independent fractionation

Kump, 2008

Warneck,2000

Methanogens

http://www.snowballearth.org/overview.html

Falkowski et al., 2005

Falkowski et al., 2005

Temperature (K)

KH

JAS, 1964

Fraunhoffer Lines

• First observed by Wollatson (1802). Fraunhoffer independently discovered them in 1814 and studied them thoroughly.

• The continuous emission of photosphere is interrupted by selective absorption and re-emission in upper photosphere. Seen in visible and IR spectra only as absorption lines. Lines at < 185 nm appear in emission.

• Fraunhoffer mapped over 570 lines. Later these lines were associated with atoms/molecules in the upper solar atmosphere.

Na O2Fe

H – Balmer series

Primary atmospheric molecules involved in

absorption of radiation

• Atmospheric molecules are characterized by discrete rotational and vibrational energy states in addition to the electronic transitions.

• Transitions– Electronic – Ionization,

dissassociation – UV some visible.

– Vibrational – IR, far IR

– Rotational – far IR, microwave

• The lower energy states significantly impact terrestrial radiation, which peaks in the IR.

Bohren and Clothiaux, 2006

Ionize Dissasociate Vibrational --- Rotational

O3

CO2

H2O

CH4