Ice thickness and temperature

Julia McFarland’s 7th Grade science class from Egan Junior High School from Los Altos, CA asks:

How thick is the ice and when you jump in how cold is it?

The ice is currently right around 1.4 meters thick or 4- 5 ft.  The water is -1.8C or 28 F.  This is two C below freezing and as cold as seawater gets before it freezes.  As soon as we jump in all of our skin that is exposed, which is only our lips, goes numb immediately so it really is not that cold after the initial shock.

You can see here that we are pretty much entirely covered up. The little sliver around our lips is all that is exposed.


The ice is slowly thickening during this time of year and at one of our dive spots it has gotten to around 12 feet.  A lot of that ice is unconsolidated “brash” ice which means if we touch it it moves more like a slushy or more like snow than ice.  Starting in mid to late November the weather warms where the sea ice is no longer thickening and it will eventually break out.  This normally happens  every year but every once in a while the sea ice will stay here for a few years creating very thick ice, in the past decade we have seen 12-18 ft of ice where we have 3 ft this year.


This is what the bottom of 12ft of ice with 6ft of snow on top looks like.the jagged ice around the side is the brash ice.

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