Stratosphere

The Stratosphere is a cosmic ball of low-density gases gradually formed over time by Rush Limbaugh's exhalations and Michael Moore's farts.

Ha ha, a fart joke. How classy.

Ecological Impact on the Biosphere

Though the gases of the stratosphere are of extremely low density, they have the streneous task of keeping the lower density gases down on the ground so people like you and me and dogs like Beethoven and Air Bud can breathe and live freely while rolling around on the grass or playing football even though you're a dog, or something.

This is an inherently difficult task, given that higher density gases are generally more powerful. The stratosphere manages to get the job done with rocket propelled grenades thoughtfully donated by the Department of Homeland Security.