The 'green flash' is due to atmospheric dispersion, and occurs when the very last part of the sun sets (or rises) if you have a cloudless horizon. Obviously looking over the sea is good, but it can be seen against distant hiils. The horizon often looks cloudless, but generally (at least for me) when the sun is on the horizon then some previously unseen cloud prevents a good green flash. It normally lasts a fraction of a second, but if say you were in a rapidly ascending plane for example, then you could see the green flash for several seconds
Thanks. But I just looked at my photo again and saw how horribly pixelated it was. I've just replaced it with one that's less jpg compressed, though it's still noisy. (It's 1:1, - no cropping in order to get the solar image as large as possible in order to maximise my chances of seeing the green flash)
I've just taken a look at your site and see that you have some fine sunsets there yourself.
