Earth's early atmosphere sim

What the sim shows

This follows one theory of how the air formed (AQA). For the first billion years volcanoes released carbon dioxide, water vapour and nitrogen, and maybe a little methane and ammonia, with little or no oxygen, like Mars and Venus today. The water vapour condensed to form the oceans, so carbon dioxide became the main gas; then it dissolved in the oceans, and carbonates settled out as sediments. Algae first made oxygen by photosynthesis (6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂) about 2.7 billion years ago, and over the next billion years plants evolved and oxygen rose until animals could evolve. Carbon dioxide fell as algae and plants used it, and as carbon was locked into sedimentary rocks such as limestone (from shells and skeletons) and fossil fuels (coal from plants; crude oil and natural gas from plankton buried in mud). For about the last 200 million years the air has been much as today: about four-fifths nitrogen and one-fifth oxygen. Today's values are real (dry air: nitrogen 78.08 %, oxygen 20.95 %, argon 0.93 %, carbon dioxide 0.04 %). The early percentages are ESTIMATES: no air from then survives, the evidence is limited, and scientists' estimates differ; "other gases" means water vapour, methane, ammonia and argon together.

• Timeline slider: drag it from 4.6 billion years ago to today
• Bell jar over a model Earth: the volcano, oceans, algae and plants appear when they did
• Rock layers: limestone and a coal seam lock carbon away

Use it in your lessons

• Try it here: anyone can unlock 2 figures free, and a free account unlocks up to 5. Runs on a laptop, a Chromebook or a phone; nothing to install.
• Present it and share student links with the teacher plan, from US$5 a month, billed yearly.
• Put it on your own website or LMS for US$9, paid once, or every sim from US$29 a month.

Free guide: 12 practicals as sims, and how to run one in a lesson →

Need a version for your exact set-up? Have one made: US$49 a figure in an order of 5.