The Atmosphere reacts, protects, and transports. Imagine a world where the daytime sky was not blue, but black. Imagine the Earth without clouds, wind, or rain. Imagine for a moment having to walk outside of your house in a space suit, just like an astronaut on the Moon! Our atmosphere is more than just hot (or cold) air. Without our atmosphere, the surface of the Earth would be subject to the harsh radiation coming from the sun. All living beings on Earth depend on the atmosphere for protection from the sun's harmful rays. In the upper reaches of the atmosphere, atoms of gas react with some of the high-energy radiation coming from the sun. These reactions absorb some of the sun's energy and prevent it from reaching the surface of the Earth where it is harmful to life. Throughout the atmosphere, winds transport clouds, precipitation, and particles across the globe. It is because of the atmosphere that heat is transferred from the equator to the mid latitudes and the Earth's poles.
The Environmental Protection Agency (EPA) monitors six criteria pollutants to make their air quality forecasts. The Aura spacecraft monitors five of the six pollutants: ozone (O3), carbon monoxide (CO), aerosols, nitrogen dioxide (NO2), and sulfur dioxide (SO2). Scientists use Aura data to monitor the production and transportation of these pollutants across the globe.
Chemical reactions in the stratosphere contribute to a thinning of the ozone layer on a yearly cycle. Without the ozone layer, high-energy ultraviolet C radiation from the sun would be able to penetrate the Earth's atmosphere and reach the ground where it would devastate all life on Earth. Transportation of chemical species called chloro-fluoro-carbons (a man-made product) from the troposphere to the stratosphere has been a major contributor to the depletion of the ozone layer. Aura scientists use data to understand the processes involved in the cyclic nature of the ozone layer depletion.
Without the atmosphere, wind wouldn't exist to spread seeds across the ocean, making it possible to carry new species to a different continent. Without the atmosphere, clouds would not exist giving our planet the characteristic appearance it has been so lovingly labeled the "blue marble".