I was watching the sun rise from behind the sea when I saw a green flash just as it came up. It was a very frosty, clear morning.
I watched again on the three following days but it came up as normal. The only other time I've seen the green flash was from the setting sun in the Indian Ocean from a merchant navy ship.
Dr Joan McGeachin
Three Mile Water, Wicklow.
You have been especially favoured. Very few people have seen the green flash on the top rim of the setting sun, and even fewer on the rising sun. The green flash is a phenomenon of physics which happens only in certain thermal structures of the atmosphere. When the sun rises or sets, its light reaches the viewer more obliquely and passes through a greater thickness of atmosphere. As this reduces the velocity of light, its rays bend at a different rate, depending on their colour, and are spread as if through a prism. The green of the spectrum is the one that survives the journey through the atmosphere.
On the very mild night of December 23rd, I saw and heard a robin singing. Is this unusual or another sign of global warming?
Kevin Gormley
Stillorgan, Co Dublin.
Edited by Michael Viney, who welcomes observations sent to him at Thallabawn, Carrowniskey PO, Westport, Co Mayo. e-mail: viney@anu.ie (please include postal address)