By Terry Eliasen, Meteorologist, WBZ-TV Exec. Weather Producer

EASTHAM (CBS) — Nearly frozen waves could be seen at the beach in Eastham on Friday. Photos of the phenomenon were tweeted at WBZ-TV meteorologists.

Slushy waves or “Slurpee waves” have become somewhat of a local wintertime phenomenon around here in the past decade or so.

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Slushy waves in Eastham on Friday (Photo Via Megan O’Leary Twitter)

So what causes them? First and foremost, you need exceptionally cold air–we certainly have that right now.

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Seawater freezes at 28.4 degrees, not 32 degrees, due to the salt content. As the ocean water begins to freeze, you get needle-like ice crystals called “frazil” to form in the water. The salt, of course, doesn’t freeze and begins to separate from the water and ice crystals.

Slushy waves in Eastham on Friday (Photo Via Megan O’Leary Twitter)

The slushy look comes from the fact that the ocean is in constant motion (unlike a lake or pond). The frazil (ice crystals) begin to collide and coalesce and meld into a slushy appearance. Of course, if the temperatures remain frigid for a long period of time, you will start to form ice chunks and sheets, something even rarer in our area.

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Just a little taste of the Arctic, right in our backyards!

Slushy waves in Eastham on Friday (Photo Via Megan O’Leary Twitter)