Hey weather gurus

............I have a strange question. I have two water features on my back deck. A plain old 80 gallon fish tank and one of those large heavy ceramic pots, about 20 gallons. The deck faces the NW and catches a lot of wind; it usually feels much colder than it actually is back there due to the wind chill. There are also a couple of bird baths nearby in the garden.

We made out OK last night and according to my thermometer we got down to 38 overnight; it dropped to 36 for about 20 minutes this morning and went back up to 38 where it has stayed all day.

We noticed the ceramic pot has a skim layer of ice on the water. Neither the adjacent fish tank or the bird baths had any ice. It doesn't make sense to me, I would have thought the bird baths would have frozen first - if the temp dropped to 32.

Why would the water in the ceramic pot get colder?

Is the pot above the ground? Up on something? Only reason I can think of is the cold air was blowing all around and under the pot. Also ceramic is used as a heat insulator which means it doesn't heat up where as other materials will heat up in the sun etc.

My best guesses.

This message was edited Jan 3, 2008 9:49 AM

It is very strange, it is up on a deck, about 6' above the ground. This morning it is frozen solid and the adjacent fish tank only has a skim on it. It is still dark and I can't see the birdbaths but the temp is below freezing so I am sure they are frozen too.