Greys in skies

I've been messing with sky photos to try to make them look better algorithmically and realized they have greys in them more than I realized (I thought my histograms of saturation were wrong at first).  Here's an example that shows a grey region between blue and orange (full at John Roever's flickr)

And one over the ocean (full photo at this Carmel page):

 And even when there is even the slightest hint of orange (from here), although there is a slight green bias:

So greys are just more common than I realized.