It’s the heart of summer, but there is still plenty of snow in the Sierra Nevada. Some of that snow has turned red. It’s referred to as ‘Blood Snow,” and it has appeared at California’s Yosemite National Park. The colorful snow is made up of clusters of algae that thrive in freezing temperatures and liquid water, resulting in algal blooms. The red or pink color is natural sunscreen for the algae’s growing on the snow. The algae that make up the red-tinted snow is officially known as Chlamydomonas nivalis, and it’s actually not red when viewed up close, but slightly green.
“These algae must contend with intense UV bombardment, they need sunscreen to protect their light-harvesting molecule chlorophyll and lots of it,” reports Scientific American
“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,” the park tweeted.