Origin of the atmosphere

Neil Savio Dsouza

The billion-eurold questions

1. Why does Earth have an atmosphere?2. What was the early atmosphere like? Why?3. How did our present atmosphere come about?

April 19, 2023 2Bremen University

1. Why does Earth have an atmosphere?

• Enough gravity [ radius, density ]

• The right temperature [ thermal velocity, states ]

• The right raw-materials [ stability ]

• Sources of gasses > Sinks

Sources Sinks

Volcanism, meteorite showers, chemical reactions, state changes

Thermal escape, solar wind, chemical reactions, state changes

April 19, 2023 3Bremen University

Lecture material, Atmospheric Physics, 2003, PEP

April 19, 2023 4Bremen University

1. Why does Earth have an atmosphere?

• Enough gravity [ radius, density ]

• The right temperature [ thermal velocity, states ]

• The right raw-materials [ stability ]

• Sources of gasses > Sinks

Sources Sinks

Volcanism, meteorite showers, chemical reactions, state changes

Thermal escape, solar wind, chemical reactions, state changes

April 19, 2023 5Bremen University

What was the early atmosphere like?

• The first atmosphere Components*: H2 & He

Sources: Space debrisSinks: Thermal escape, Solar wind

Lost to space

April 19, 2023 6Bremen University

What was the early atmosphere like?

• The second atmosphereComponents: H2O, CO2, SO2, CO, S2, N2, H2, NH3,,CH4, O2*

Sources: Volcanism, photolysis, meteoritesSinks: chemical reactions(CO2,O2), state changes(H2O)

Magnetosphere develops*

April 19, 2023 7Bremen University

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http://www.multinet.no/~trojen/australia/pages/australia%20-%20limestones%202.htm

What was the early atmosphere like?

• The second atmosphereComponents: H2O, CO2, SO2, CO, S2, N2, H2, NH3,,CH4, O2*

Sources: Volcanism, photolysis, meteoritesSinks: chemical reactions(CO2,O2), state changes(H2O)

Magnetosphere develops*

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http://scijinks.jpl.nasa.gov/en/educators/gallery/spaceweather/solar_wind_comp_L.jpg

How did our present atmosphere come about?

April 19, 2023 11Bremen University

How did our present atmosphere come about?

April 19, 2023 12Bremen University

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http://www.ggl.ulaval.ca/personnel/bourque/s4/stromatolites.html

How did our present atmosphere come about?

April 19, 2023 14Bremen University

How did our present atmosphere come about?

• Growth of oxygen

Lecture material, Atmospheric Physics, 2003, PEP

April 19, 2023 15Bremen University

Summary

• Earth retained an atmosphere because it had optimal gravity and temperature to sustain one.

• Lithosphere, Hydrosphere and biosphere together have contributed to out present atmosphere

• Interactions between them must be considered to fully understand the state of our atmosphere at any time.

April 19, 2023 Bremen University 16