To download, simply hit the "download" button and accept, then google will install it for you! please enjoy.
On the chrome web store [link]
You can also get the wallpaper version of the background from [link]
I don't know if you still pay attention to the comments for this post, but I found this chrome theme back when I was in high school not long after you posted it. It's been my chrome theme for the last eleven years. I never changed it in that whole time. But last year some chrome updates made the theme hard to use, so I finally caved a while back and swapped it out. But this theme has been with me for so long. I will miss it. Thanks for making it :)
One note though...
I was expecting the active tab to be highlighted, not the other way around... Is there any way to change this? Or could we expect a Dark Atmosphere II in the near future?
Oh, and I agree with ojaebu; it would be nice to have the scroll bar in a darker shade too, just as the rest of the screen.
Other than that, nice, easy on the eyes, clean interface!