[muawiyah]

As the Sun sets in the evening you see blue sky turn into red sky. In between, in the blink of an eye, you may see it turn to green ~ it'll look like a streak of green light.

You usually don't get a good look at it in humid atmospheric conditions. The air has to be exceptionally dry, and that's probably a rare event in the vicinity of Singapore.

[RightWhale]

The green flash is well known but rarely seen. Usually the sun itself flashes green as it sets if it is going to happen, but north of here refraction is so bad the sun often doesn't set but fades to zero while still slightly above the horizon. Saw the sun at Prudhoe Bay a good three hours after sunset. It never set at all and it didn't give the green flash either.