Blue sky?

I worked nine to five today.  As I walked across from the car park, there was blue sky.  I liked the sky, with 2 layers of clouds - high white fluffy ones (I think they are cirrocumulus?) and the grey ones drifting much lower.

By the time I went outside again, at about 1030, the sky was completely overcast.

And of course it was dark before I left for home.