Watermelon snow
| Chlamydomonas nivalis | |
|---|---|
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| Scientific classification | |
| Kingdom: | Plantae |
| Phylum: | Chlorophyta |
| Class: | Chlorophyceae |
| Order: | Volvocales |
| Family: | Chlamydomonadaceae |
| Genus: | Chlamydomonas |
| Species: | C. nivalis |
| Binomial name | |
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Chlamydomonas nivalis (Bauer) Wille |
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Watermelon snow, also called snow algae, pink snow, red snow, or blood snow, is Chlamydomonas nivalis, a species of green algae containing a secondary red carotenoid pigment (astaxanthin) in addition to chlorophyll. Unlike most species of fresh-water algae, it is cryophilic (cold-loving) and thrives in freezing water. Its specific epithet, nivalis, is from Latin and refers to snow.
This type of snow is common during the summer in alpine and coastal polar regions worldwide, such as the Sierra Nevada of California. Here, at altitudes of 10,000 to 12,000 feet (3,000–3,600 m), the temperature is cold throughout the year, and so the snow has lingered from winter storms. Compressing the snow by stepping on it or making snowballs leaves it looking red. Walking on watermelon snow often results in getting bright red soles and pinkish trouser cuffs.
The first accounts of watermelon snow are in the writings of Aristotle. Watermelon snow has puzzled mountain climbers, explorers, and naturalists for thousands of years, some speculating that it was caused by mineral deposits or oxidation products that were leached from rocks.
In May 1818, four ships sailed from England to search for the Northwest Passage and chart the Arctic coastline of North America. Severe weather made them finally turn the ships back, but the expedition made valuable contributions to science. Captain John Ross noticed crimson snow that streaked the white cliffs like streams of blood as they were rounding Cape York on the northwest coast of Greenland. A landing party stopped and brought back samples to England. The Times wrote about this discovery on December 4, 1818:
A follow-up article three days later erroneously concluded that the coloration was caused by meteoric iron deposits:
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Wikipedia