Friday Fotos: Sky

I've decided to follow last week's minimalist focus on surfaces with more minimalism: sky. Sky of course is ubiquitous in the external world and so I've got scads of photos with sky in them somewhere. I've even got lots of photos that are mostly sky. So I decided to use only photos that were all sky in the sense that there is nothing in the image that is attached to the ground. That left me with very few photos, and those of a rather limited range. Still there is some variety. But very few of my sunrise or sunset photos – of which there must be 100s – meet this criterion, because almost all of them show a strip of land, water, or city at the bottom.
Here's the first such photo I found when I went looking through my Flickr collection:

Such a photo would have been impossible before the middle of the previous century as that white streak, a contrail, betrays the existence of a jet aircraft. Herewith, the other photos without comment: