Home About Us Climate Change FAQ's Contact Us Join Latest News on Carbon Conservation Real-World Climatology: Records and Observations Reference Center Signup For E-mail Alerts Virtual Climate Alerts World Climate Report Online Sitemap All this takes place at an altitude of 160 - 180 to 600 - 700 km. But above? Who can compete with the O atoms, if with O2 and N2 are finished at the bottom? Only other atoms. We have already cited as an example of some of the figures for speed increasing the concentration of helium (remember that helium is 4 times lighter oxygen - its atomic mass is equal to 4). At the level of the amount of helium turbopause negligible - about one atom Not for 104 of the surrounding molecules. But according to the laws of molecular diffusion of its relative concentration continuously and rapidly. And above 600 km it comes to fighting atomic oxygen. And, of course, wins. But his reign comes to an end. It displaces more light gas - hydrogen, which is four times lighter than helium. The amount of hydrogen in turbopause even less than helium (about 9.10 of the total number of particles), but the diffusion separation to him more favorably. So in the end, he becomes the main atmospheric component (concentration of H and compared on heights of 1500 - 2000 km). With no one left to compete with hydrogen - the lightest gas. Therefore, it remains the main component of the atmosphere until its "end", that is, until that very blurred boundary where the exosphere goes into interplanetary gas, too, by the way, and consists primarily of hydrogen. So, everything that we covered in this section can be summarized very briefly. To height of 105 - 110 km mixed atmosphere and its composition is constant. Begins to rise above the share lighter gases. To a height of 160 - 180 km is dominated by molecules (mainly N2). Then they are replaced by oxygen atoms dominate the height of 180 - 600 km. From 600 to 1500 km the main component of the atmosphere, helium, and above - hydrogen. It seems that everything is simple and clear, and the problem of the composition of the atmosphere can be put point. And it would indeed be the case if it were not for the strong variability of the composition.