Sydney winter day.
edit to add: actually, on reflection, it is not so much iridescent as glary. Sorry if this introduces a note of confusion for overseas readers. I wrote this post quite early and had the impression of iridescence creeping in through the windows, which had the blinds lowered.
I wouldn't just want to be seen as a booster for all things Sydney, here. If it is a beautiful, glorious or iridescent day, you will know the truth of it. If on careful reflection things turn out to be overcast or gloomy, you need to know that this is a blog which will correct its inevitable mistakes.