Gold Dome Physics Mystery...

Folks in our new residential community learned that I knew a bit about science and asked me what was happening with the dome they saw out their window. The first image here is a picture of the St. Katherine Greek Orthodox Church just down the street in my new neighborhood in Naples, Florida. Like almost all Greek Orthodox churches, its most prominent architectural feature is a doom covered in Gold leaf. The expectation is that every time you drive by it will look about like that image.

But it dose not. Often it is totally black, like the second image. In the last two images, the dome is “motley,” part black and hints of gold. A quick look at an aerial view of the dome from Google Earth appears to assure us that it is black, indeed.

The church claims that the gold leaf is just that …. 23.8 carat gold foil …. adhered to a clean underlayment …. just like it was done in medieval times. Today, gold leaf is commercially available in big sheets with a backing cover and a peel-away protective layer. Craftsmen cut it up with scissors. Before it is pounded super thin, the gold needed for a dome like this would fit in the palm of your hand. The real cost is those skilled craftsmen’s time. Some still belong to an ancient goldsmiths guild and travel from city to city around the world brightening domes.

But I digress.

I ruled out various theories that differences in appearance could be because of polarized sun glasses, polarized windshields, exotic window-coating-films, etc. With no glasses and my window rolled down I have taken many pictures similar to those above. A solid hint may be that a clear blue sky causes the dome to look black while gold observations seem to occur on overcast days. The “half and half” picture just above was taken on a sunny day, but with clouds around us.

The theory that the gold dome reflects clear and cloudy sky differently is reinforced by this. But I am at a loss as to how to explain it.

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This is a follow-on to a previous post…