The science of pink "watermelon snow"

In this Weather Wednesday we look at why snow can naturally be pink but it isn't something we should love.

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FARGO - We are used to being surrounded by white snow in the winter, but sometimes snow can be pink and its not from snow sprays or food coloring.

It’s called watermelon snow due to its color and reportedly similar smell to the summer fruit. But unlike summer algae blooms in the lakes, this algae is cryophilic, it loves the cold and thrives in freezing water, often forming in the mountains and at altitudes above 10,000 feet.

Watermelon snow is more common during the late spring and summer months and has been found on all continents.

It can look like pink or red shaved ice, but this is no snow cone and don’t even think about eating it, the snow and melted water from it can have a laxative effect.

The pink color comes from a species of green algae containing a red carotenoid pigment in addition to chlorophyll, just like how some leaves trade their green color for the red hues in the fall.


And while this pink snow may look spectacular, its nature is quite sinister for any glacier it forms on. The darker red and pink color absorbs more sunlight, lowering the albedo, or reflectivity, of the snow by as much as thirteen percent, aiding in the melting of glaciers and snow faster.

As this process continues, more algae are able to bloom and propel the process further. Certainly not something to love, but if you do come across it, you can collect a sample of the snow algae and send it to researchers with the Living Snow Project .

Jesse Ritka is a StormTracker meteorologist and holds the AMS Certified Broadcast Meteorologist seal of approval.

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