In this deck, we'll explore the fascinating story of Earth's atmosphere. We'll look at the mixture of gases we breathe today and travel back billions of years to understand how scientists believe the early atmosphere formed. We will cover the role of volcanoes, the formation of oceans, and how the evolution of life itself dramatically changed the air, paving the way for us.

Let's start with the air around us right now. Earth's modern atmosphere is a mixture of gases. The vast majority, about eighty percent, is nitrogen. The second most abundant gas, at about twenty percent, is oxygen, which is essential for most life on Earth. Other gases like argon, carbon dioxide, and water vapour make up the remaining small fraction.