Thanks to the Alamanac in OP I can look up the azimuth of sunrise and sunset anywhere in the Northern Hemisphere, and it's easy to get the time. So fine: I go to a beach somewhere and set up my camera at the correct azimuth and wait until the correct time and get a very boring sunset! No picture! Often there are heavy clouds on the horizon, which give a hint that things won't be so good, but you never know so I wait, and my wife, who often has to wait with me, is not enthusiastic. Does anyone know how, by looking at the sky half an hour or an hour in advance (or by any other method, for that matter) to predict whether a sunset will be worth waiting for? Same question for sunrise?