173 Skybathing

Could anyone explain how beautifully it can refresh and sharpen up people just to look at and take some air from very early morning sky?

I think this is not just a mental effect of feeling good. It should be something substantial, scientific action working on.

It's different from the sunlight-bathing. Sun has not even appeared.

What's that thing seriously that makes me feel terribly great when looking at the break of dawn?