[Uncle Blue]

Uncle Blue asked the Naked Scientists:
   
Dear Drs

In Sweden where i live, we are used to cold winters, down to - 30 C. The coldest nights are the clear ones, when there are no clouds to keep what warmth the sun brought in the day time.

But Why does this coincide with the full moon so often? Almost all winter, moons can be seen on clear night skies.

What do you think?

[Karsten]

But Why does this coincide with the full moon so often? Almost all winter, moons can be seen on clear night skies.

Is that a feeling or are there hard, cold numbers and records to support this statement?

Are the skies clear because there is a full moon or can you see a full moon only/better on days when the sky is clear?

[acey]

As an amateur astronomer (in UK) I have also noticed this (to me) annoying tendency: I can only observe faint galaxies on cloud-free nights with no bright Moon, but the clearest nights seem to come around full Moon.

I've put it down to selective bias that would not be borne out by numerical data, but on a UK astronomy forum I saw a posting from a member who has been keeping records, and finds there is indeed some correlation. Many amateur astronomers have noticed this apparent effect (often putting it down to what we Brits call "sod's law", i.e. bad luck).

I understand that "official" opinion remains that there is no effect, but I am interested to see the same anecdotal observation coming up here.

I have wondered if there might be some correlation between tides and cloud cover. I'm not aware of any studies having been done on this, it would be very interesting to know if any work has been done.

[acey]

Follow up: it was full Moon last night. And guess what... a crystal-clear, cloudless night.

[Karsten]

Ironically, same here in Southern Quebec.

You might find this article helpful:
http://www3.interscience.wiley.com/journal/21849/abstract?CRETRY=1&SRETRY=0
"Statistical analysis of 44 years of data has shown no apparent correlation between a clear sky and the occurrence of the full moon"