I see I have already posted on this phenomenon before, because I have created a label for "termination dust." In order to save you the trouble of searching this blog for that label, I will repeat myself, as Walt Whitman did indeed say.
In the old days, when a prospector's claim ran out, he would start getting dust instead of nuggets in his pan (or whatever system he was using), and this was termination dust. Claim done. So nature gives us a similar signal" summer done.
Unfortunately my zoom feature has ceased. I fear my camera has therefore deceased too. Well, out on the back porch, we can just see dawn, and snow dust on the Chugach range. But there it is. The Fireweed has folded up. The birches turn yellow. Winter is upon us. Part of the fun of living in Alaska. Here in suburbia I can't go out and cut firewood. But we must accept change. The year wheels.