ESS200A
Prof. Jin-Yi Yu
Origins of the Atmosphere
qWhen the Earth was formed 4.6 billion years ago, Earth’s atmosphere was probably mostly hydrogen (H) and
helium (He) plus hydrogen compounds, such as methane (CH4)
and ammonia (NH3).
èThose gases eventually escaped to the space.
qThe release of gases from rock through volcanic eruption (so-called outgassing) was the principal source
of atmospheric gases.
èThe primeval atmosphere produced by the outgassing was mostly carbon dioxide (CO2) with some Nitrogen (N2) and water vapor (H2O), and trace amounts of other gases.