Watermelon Snow
by Jon Burch Photography
Title
Watermelon Snow
Artist
Jon Burch Photography
Medium
Photograph - Digital Capture
Description
Watermelon snow, also called snow algae, red snow, or blood snow, is caused by a species of green algae containing a secondary red carotenoid pigment in addition to chlorophyll called Chlamydomonas nivalis. Unlike most species of fresh-water algae, it is cryophilic or 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, 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 and often results in getting bright red soles and pinkish pant cuffs.
Chlamydomonas nivalis is a green alga that owes its red color to a bright red carotenoid pigment, which protects the chloroplast from intense visible and also ultraviolet radiation, as well as absorbing heat, which provides the alga with liquid water as the snow melts around it. Algal blooms may extend to a depth of 10 inches, with each cell measuring about four times the diameter of a human red blood cell. It has been calculated that a teaspoon of melted snow contains a million or more cells. The algae sometimes accumulate in "sun cups", which are shallow depressions in the snow. The carotenoid pigment absorbs heat and as a result it deepens the sun cups, and accelerates the melting rate of glaciers and snowbanks.
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.
A glacier is a persistent body of dense ice that is constantly moving under its own weight; it forms where the accumulation of snow exceeds its melting and sublimation over many years, often centuries. Glaciers slowly deform and flow due to stresses induced by their weight, creating crevasses, seracs, and other distinguishing features. They also abrade rock and debris from their substrate to create landforms such as cirques and moraines. Glaciers form only on land and are distinct from the much thinner sea ice and lake ice that form on the surface of bodies of water.
On Earth, 99% of glacial ice is contained within vast ice sheets in the polar regions, but glaciers may be found in mountain ranges on every continent except Australia, and on a few high-latitude oceanic islands. Between 35 degrees N and 35 degrees S, glaciers occur only in the Himalayas, Andes, Rocky Mountains, a few high mountains in East Africa, Mexico, New Guinea and on Zard Kuh in Iran. The ice in this mountain cirque is located at the top of Trail Ridge Road in Rocky Mountain National Park, northern Colorado.
Image copyright 2014 Jon Burch Photography
Uploaded
June 28th, 2014
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