Snow bloom refers to the rapid growth and increase in numbers of so-called snow algae on the surface and interior of snow fields. Typically occurring as the surface of the snow warms in the springtime sun, the algal growth confers various colors to the snow. Colors of different algal species include yellow, red, green, and orange.

Blooms occur when nutrients are abundant and conditions such as temperature are conducive to rapid growth. "Red tide," due to the growth of a diatoms in salt water, is another example of a bloom.

There are some 350 species of snow algae. A common species is Chlamydomonas nivalis.

Snow algae have been known for millennia. The Greek philosopher Aristotle described red snow over 2,000 years ago. The algal basis for the blooms was determined in the early nineteenth century, when some red-colored snow obtained by a...