What are the main constituents of the earth's atmosphere in our time?
The present atmosphere of the earth is constituted essentially of molecular nitrogen (N2) and molecular oxygen (O2). Nitrogen is the majority abundant gas, approximately 80% of the total volume. The Oxygen makes up about 20% and other gases exist in the atmosphere in a low percentage (Of great concern is the increase in the amount of carbon dioxide due to human activity, the cause of the threatening global warming).