The Early Atmosphere

  • Earth's first atmosphere 4.6 billion years ago was most likely comprised of hydrogen and helium (two most abundant gases found in the universe!)

  • Through the process of outgassing, the outpouring of gases from the earth's interior, many other gases were injected into the atmosphere. These include:

    • water vapor (produced rain - rivers, lakes, oceans)

    • carbon dioxide

    • nitrogen

  • As outgassing occurred over a period of millions of years, the atmosphere evolved to its current state