Comparing the Early and Current Atmosphere

Flashcards covering the composition and changes of Earth's atmosphere from 4.5 billion years ago to the present day based on lecture notes.

Earth's Atmosphere

The relatively thin layer of gases surrounding the planet, held close by gravity.

Age of the Earth

Earth formed approximately $4.5$ billion years ago.

Volcanoes

Natural features common on early Earth that released large volumes of carbon dioxide and water vapour.

Early Atmosphere: Carbon Dioxide

The most abundant gas in the early atmosphere, making up $95\%$.

Early Atmosphere: Water Vapour

A gas released by volcanoes that made up $4\%$ of the early atmosphere.

Early Atmosphere: Oxygen

A gas that was not present ($0\%$) when the Earth first formed.

Early Atmosphere: Minor Gases

Traces of nitrogen, ammonia, and methane, which collectively made up about $1\%$.

Current Atmosphere: Nitrogen

The gas with the highest abundance in the current atmosphere, making up $78\%$.

Current Atmosphere: Oxygen

A gas that currently makes up $21\%$ of the atmosphere.

Current Atmosphere: Carbon Dioxide

A gas that has decreased from its early levels to a current concentration of $0.04\%$.

Current Atmosphere: Argon

A gas that currently makes up less than $1\%$ of the atmosphere.

Trend: Carbon Dioxide

This gas has decreased from $95\%$ in the early atmosphere to $0.04\%$ today.

Trend: Oxygen

This gas has increased from $0\%$ in the early atmosphere to $21\%$ today.

Trend: Nitrogen

This gas has increased from trace amounts in the early atmosphere to $78\%$ today.

Trend: Water Vapour

This gas has decreased from its early composition of $4\%$ to trace amounts today.