green flash at sunset

[con-amca]

I have been told, more than once, that at the instant the sun sets into the sea, a green flash can sometimes be seen just for a fraction of a second. I've never been able
to make up my mind whether this is true, or I'm having my leg pulled. I've certainly never seen such a flash, green or any other colour. Can anyone shed any (flash of) light on this?

[Azalian]

The green flash is a real phenomenon, caused ( I think) by the last rays of the sun passing through the surface water of the sea.

The sea needs to be very calm to show it though, in ten years at sea I only ever saw it once.

Hope this helps.

[heathfield]

I've seen it several times. It's caused by denser air lying on the sea surface refracting the red light upwards and away from your line of sight. The denser air layer is only 3 or 4 feet deep, and wind or waves will break it up, so calm conditions are necessary. It's best recorded on video, as it can happen too quickly for taking with a still camera. Look up 'green flash' on Google for lots of images. This one is quite typical.

[con-amca]

Well!! Thank you both, very much. I've always been sceptical of this; it seemed the sort of story leg-pullers love to put about, like the one about all pomegranates, irrespective of size, having the same number of pips. But you've confirmed it. I've watched for it many times, in the
Black Sea of all places, but without success.

Is someone now going to come along and tell me that yes, all pomegranates do have the same number of pips?

[CT]

Some more examples here
http://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_ search?green+flash