A special kind of “watermelon snow” has just been spotted high up in Yosemite National Park in California, but you should not confuse it with the beloved summertime treat.

The national park took to social media last weekend to share photos of the unusual-looking snow at an unnamed lake in the high country above 9,500 feet.

“It may be August, but there is still plenty of snow and ice above 9,500 feet!” the park tweeted. “This reddish colored snow is often called watermelon snow.”

It may be August, but there is still plenty of snow and ice above 9,500 feet! This reddish colored snow is often called watermelon snow. The red or pink color is the usually green algae’s natural sunscreen, protecting itself from too much heat and damaging UV radiation. pic.twitter.com/bfOSIadT4l

— Yosemite National Park (@YosemiteNPS) August 5, 2019

Watermelon snow, which is also known as “red snow” or “blood snow” is what happens when snow above 9,500 feet lasts through the summer months. The unusual color is the result of cold-loving algae known as Chlamydomonas nivalis, which lives on the snow and “thrives” in temperatures below freezing and liquid water.

“This algae is typically green but contains a special red pigment called a carotenoid that acts as a protective barrier, shielding the algae’s chlorophyll,” park rangers explained. “Since chlorophyll is necessary for its survival, it uses this natural type of sunscreen to protect itself from too much heat and damaging UV radiation.”

While watermelon snow looks beautiful in pictures, rangers have warned hikers to be careful about trying to photograph it because trails in the high county have less than ideal conditions at the moment that include snow, mud, water crossings, and other hazards.

“Hikers and backpackers should be aware that trail conditions can change throughout the day. If conditions are not ideal for you, turn back, and try your hike or backpacking trip another time,” park officials said. “It is not worth risking your safety to finish your hike.”

 

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Watermelon Snow (or Blood Snow) between Burroughs peaks 2 & 3. Aristotle wrote about it, and it puzzled high alpine and coastal explorers for thousands of years. Turns out it’s just a green algae that has a natural red pigment that protects it from bright UV light. #watermelonsnow #bloodsnow #hiking #washingtonstate #pacificnorthwest #scienceiscool

A post shared by Tim Joyce (@seattlejayhawk) on Jul 31, 2019 at 12:03pm PDT