Watermelon snow turns Utah’s mountains pink and red


The people of Utah saw snow on the ground tinged with a red and pink hue.

It’s certainly pretty to look at, but what’s behind the natural phenomenon that’s nicknamed “watermelon snow”?

Experts say it’s a normal occurrence that occurs in mountainous locations around the world.

While you might not guess it from the colors of the snow, it’s the result of green algae blooms that thrive in cold, snowy environments, according to Scott Hotaling, an assistant professor in Utah State University’s science department.

It’s called the species of algae that causes Utah’s colored snow Chlamydomonas nivalis.

Hotaling said that although Utah’s snow appeared red — the most common color of the phenomenon — there are types of algae that live on the ice and snow that can turn the usually white frozen precipitation all kinds of colors, including purple, green and orange. .

“(The algae are) normally in this kind of dormant cyst form, and when there’s enough meltwater in the snowpack and enough nutrients, like in the spring, that cyst form is triggered from dormancy,” he Hotaling told CNN.

Pink snow in Cache County, Utah, is pictured on Wednesday, June 21, 2023.

“It has this little flagellum that can swim through the snowpack to the surface, (where) it experiences a lot of solar radiation and blooms,” Hotaling said.

That bloom is a sign of the algae’s reproductive stage, during which a secondary pigment is created that darkens the algae’s cells, according to Hotaling.

This pigment acts as a UV blocker that protects algae cells from solar radiation.

“I have very fair skin, I have a lot more struggles with the sun than people who have much more pigmented skin — same idea for algae,” Hotaling said.

As the algal cells heat up in the sun, they melt the water around them that was previously snow, he explained, which releases water into the frozen environment.

There are no human health concerns for water quality and for anyone who comes into contact with the watermelon snow, according to Hotaling.

States in the western United States such as California, Utah, and Nevada have suffered from drought that hasn’t left much snow in those areas in recent years, CNN senior meteorologist Brandon Miller said.

“This year, they saw a huge amount of record snow in some locations, so the snow depth was very deep, a lot of snow to last into the summer,” Miller said.

“For some, it’s probably the first time in years that they’ve been able to see this phenomenon just because of the busy snow year we’ve had in this part of the world,” he said.

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