Wednesday, March 3, 2021

Blue Ice

Last night lots of ice blew up on the shore across the street from the school.  We know it was blowing at least 55 mph (about 88 kph) because the bridge was closed to high-profile traffic for about an hour last night.

It may have been right across the street, but we had to take a "field trip" to check out the blue ice the kids had heard about on the news.

I did some research, because you know,  I'm nerdy; I wondered why the ice is blue some years but not others. Apparently the  ice isn't really blue - it just appears blue. It's all about how much light can penetrate the ice. On years like this one, when the ice freezes slowly there are fewer air bubbles and larger ice crystals. That combination allows light to penetrate deeper into the ice. Six times more red light is absorbed by the ice than blue light (remember, white light is made up of all the colors of the visible spectrum.) Since that red light isn't reflected back to our eyes, the ice looks blue.

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