'Watermelon Snow' Colors Utah's High Mountains

Jun 28, 2023

“Watermelon snow” sounds like a tasty summer treat. But it's actually a biological event happening right now that’s turning the snow in Utah’s high mountains shades of pink and red.  

Mountains all around the world can have this colorful snow. It happens because of a green algae named Chlamydomonas nivalis. This algae grows a lot this time of year. Visitors to the mountains in Cache County, northern Utah, have been taking many pictures of this strange event in recent days.

There are lots of different algae living on these mountain slopes. When some of the snow melts, the algae begin to grow. This can make the snow different colors. 

Scott Hotaling is a Utah State University professor. He told CNN that the algae is usually in a sleeping form. But, when the snow melts and there is enough nutrients, the algae can wake up.  "(It) can swim through the snowpack to the surface, (where it) experiences a lot of solar radiation and it blooms.” 

The algae then creates a color that helps protect it from too much sunlight and makes the snow darker. 

Weather experts think that lots of snowfall this past winter probably caused more snow to stay on the ground later into the year. So more people could see this colorful snow. Some people who walk on it get stained shoes and clothes. 

Hotaling warned people not to eat the snow, even though watermelon snow is probably not worse than the regular kind.    

Photo by Kory J. Collier courtesy of Wikimedia Commons. 

Reflect: What strange things in nature have you seen before? Explain.

The author’s use of a cause and effect text structure helps support the reader’s understanding of _______. (Common Core RI.5.5; RI.6.5)
a. how to take pictures of the colorful snow using cellphones
b. how the pink and red snow looks different from regular snow
c. why the snow in Utah's high mountain passes is turning various shades of pink and red
d. how much snow falls in different mountain ranges around the world
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