While in popular terminology "air" is often conflated with "oxygen," air actually consists of oxygen and a mixture of other gases, such as nitrogen, methane and carbon dioxide. In fact, every breath you take contains methane, a gas that could kill you if breathe too much of it. In addition to supplying the oxygen you need to survive, air is an important part of several essential cycles that also make life on Earth possible.
Air and the Water Cycle
While the oceans contain most of the planet's water, water also exists as ice and water vapor. Air is important because it helps water move between these states in a process scientists call the water cycle. Heated by the sun, surface water evaporates into the air and becomes water vapor. As temperatures drop, water vapor forms clouds as it condenses. Clouds return water to the ground in the form of rain, sleet or snow. Because clouds move, they often transport water to locations far from where the water originated. The water cycle ensures that life around the planet receives the water it needs. It also helps replenish lakes, rivers and other waterways.
Air and the Carbon Cycle
Air plays a vital role in recycling one of Earth’s most important substances: carbon. Carbon is important because you are a carbon-based life form and you need it to survive. Carbon sources include fossil fuel combustion, the decay of dead animals and volcanoes. Animals and humans also release carbon dioxide into the air when they breathe. Through a process called photosynthesis, plants extract carbon dioxide from the air and use it to produce energy. They also release oxygen during this process. When people and animals eat the plants, they ingest carbon and produce the energy they need to live. When they die, their bodies decompose, causing carbon to go back into the air as this endless cycle repeats itself.
Air: Earth's Comfort Blanket
Without air, average temperatures on Earth would plummet to below freezing. During the day, the planet gets warm as it absorbs energy from the sun. Through a process called the greenhouse effect, carbon dioxide and other greenhouse gases absorb some of the infrared radiation the earth releases as it cools. This heat in the atmosphere causes the earth’s surface to warm as well.
Air Protects You
Earth’s atmosphere helps protect you from X-rays, cosmic rays and other particles that bombard the planet. Earth’s ozone layer helps reduce the amount of harmful ultraviolet radiation that reaches the surface. Air also reduces the possibility that meteorites and asteroids could level a city. Most space rocks vaporize in the air before they reach the ground, where they can cause destruction. Earth’s atmosphere also helps moderate temperatures so that its surface isn’t too hot or too cold to support life.
Other Interesting Air Facts
Imagine not being able to hear a screaming jet engine a foot away from your ear. That’s what would happen if air did not exist. People can hear sound only because air carries sound waves from one point to another. Eliminate air, and nobody will ever hear sounds that move between locations. Because air molecules cause violet and blue wavelengths of sunlight to scatter, the sky appears blue. With no air, the sky would always be black. You can also thank air for rain, snow and tornadoes, because air helps create weather. Storms, for example, often occur when a cold air mass collides with a warm air mass. An air mass is a body of air that acquires the temperature of the area over which it resides.
- Newton Ask a Scientist: Breathing Gas Mixture
- NASA: What is Aerodynamics?
- Fundamentals of Forensic Science; Max M. Houck, Jay A. Siegel
- Advanced Aircraft Design: Conceptual Design, Technology and Optimization of Subsonic Civil Airplanes; Egbert Torenbeek
- Universe Today: How Does the Earth Protect Us From Space?
- Rice University Museums Teaching Planet Earth: Why Do We Care About the ATMOSPHERE?
- U.S. Environmental Protection Agency: The Greenhouse Effect | A Student's Guide to Global Climate Change
- U.S. Geological Survey: Water in the Atmosphere, the Water Cycle
- Spark Science Education Kids' Crossing: The Carbon Cycle