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Depending on the circumstances, a landscape coated with snow can be a winter wonderland, a major nuisance, or a disaster in the making. There’s another way to view the white stuff as well, because snow can provide an important resource for doing science.

Both scientists and photographers have long studied and photographed the astonishing beauty of individual snowflakes. Here we’ll concentrate on snow that has reached the ground. We’ll explore some of its characteristics and effects on the environment, aside from the moisture it provides.


Sapling conifers like this one near Cloudcroft, N.M., form heat islands that melt surrounding snow, especially when sunlight warms their needles.

Snow as a Heat Island Indicator

The temperature measured by many of the ever-diminishing number of climate monitoring stations around the world is biased in the warm direction by improper site selection or by changes at sites that were properly located when they were first installed.

In 2007 meteorologist Anthony Watts became concerned about this problem and began a project to survey all the climate monitoring stations in the United States Historical Climatological Network (USHCN). Watts’ project has so far provided photographs and detailed descriptions of 1,003 of the 1,221 USHCN stations surveyed by Watts and his volunteer team of citizen scientists.

The most alarming finding from this study is that many stations are placed much too close to “heat islands” such as buildings, pavement, sidewalks, driveways, and even the hot exhaust from air conditioners. Only 10 percent of the stations surveyed meet the National Oceanic and Atmospheric Administration’s (NOAA) two highest rankings for climate stations. Full details of Watts’ project are at

Watts and others have used expensive infrared viewers to see how weather stations are influenced by nearby heat islands. Snow can also indicate a warming bias, and it can be easily recorded by an ordinary camera.

There is likely a problem if snow melts more rapidly in the vicinity of a temperature station than in a nearby open area. The temperature-sensing apparatus itself and its mounting hardware can provide a slight warm bias. But the most significant warming is often caused by nearby roads, parking lots, and buildings.

Snow also provides an ideal tool for photographing and studying natural heat islands. For example, rocks emerging through snow will quickly warm when exposed to sunlight and melt nearby snow. Stumps and living vegetation will also become warm and cause melting. This provides interesting clues about the survival of insects and microorganisms during winter.

You can do a variety of experiments that illustrate how heat islands affect snow. The simplest is to place various objects on snow in an open area with plenty of sunlight. Sheets of black and white construction paper will work if there is no wind. Take photos of the objects and the surrounding snow before and after the sun has done its work.

Snow as a Particle Collector

During the spring of 2004, fires in Southeast Asia sent smoke plumes across the Pacific Ocean to the United States. When the Navy Research Lab’s NAAPS aerosol forecast ( showed that smoke would arrive in New Mexico, I headed west from Texas in my old pickup in an effort to both measure the smoke and capture some of it for study. Along the way, a homemade air sampler mounted on the truck blew air collected by a funnel over the sticky side of a piece of adhesive tape. (I’ll provide details in a future column.)

The air sampler proved its worth by collecting mineral grains, fungal spores, pollen, and other matter while driving along West Texas and New Mexico highways. But it failed to collect any of the microscopic particles of coal-black soot that form smoke. The Asian smoke remained high overhead and none of it fell to the surface while I was sampling. The smoke covered much of New Mexico, but when I arrived in Las Cruces on March 25 it was much too high to be captured.

Finding particles of smoke that might have fallen from the smoke clouds before I arrived in New Mexico would require a very different kind of collector, so I headed for Cloudcroft in the nearby Sacramento Mountains. The NAAPS forecast showed that smoke particles fell to the ground over that region on March 16–17.

Large patches of snow remained in the mountains, and they were coated with a surprising amount of dust. The snow under the dirty layer was much cleaner. The NAAPS model showed that a large dust storm had blown across the mountain on March 5.

In effect, the patches of snow served as giant air samplers that captured and stored whatever was falling from the sky. While smoke particles were the main objective, the dust provided a bonus. It was time to place a drop of melted snow on a glass slide and inspect it through a microscope.

A single drop of snowmelt from the dirty layer contained hundreds of fungal spores and many thousands of tiny grains of gypsum. Also present were plant matter, transparent orange crystals, and what appeared to be a few slivers of volcanic glass.

Dozens of samples were inspected, and many included dark black particles of soot scattered among the tiny grains of gypsum dust and sand. The soot was presumably from the Southeast Asian smoke that fell across the region the week before.

The obvious question about the fungal spores was, did they arrive with the dust or the smoke? Or maybe they blew from nearby evergreen trees?

The smoke hypothesis can’t be ruled out. When my daughter Sarah was in high school, she discovered many spores and bacteria in biomass smoke that arrived in Texas from the Yucatan Peninsula. She established this beyond a reasonable doubt by capturing spores arriving with smoke from the Yucatan by means of a homemade air sampler she flew from a kite at the edge of the Gulf of Mexico.

This discovery became a “fast track” paper in Atmospheric Environment, a leading scientific journal (see

While spores can probably be blown across the Pacific, it’s much more likely that those in my snow samples came from much closer sources, such as nearby trees. In any event, it was quite a surprise to find so many fungal spores in snow atop a mountain. The spores included the genuses Alternaria, Nigrospora, Curvularia, Cladosporium, Penicillium (or possibly Aspergillus), and what resembles the ascospores Splanchnonema and Leptosphaeria.

I was unable to identify the most common spore in the snowmelt, as it’s not shown in E. Grant Smith’s Sampling and Identifying Allergenic Pollens and Molds (Blewstone Press, 2000) or Bryce Kendrick’s The Fifth Kingdom book and CD (Mycologue Publications, 2000).

Going Further

If you reside in snow country, what’s in your snow? Does apparently pristine snow contain fungal spores and protozoa? Is it contaminated with soot particles? If these and other contaminants are present, can you use satellite imagery to back-track the storm that dropped the snow, thereby possibly finding where the contaminants originated?

How do plants buried under snow exploit the heat islands formed by rocks and stumps?

What are the simplest and most efficient ways to melt snow outdoors? Ashes? Sand? Sunlight reflectors? Reusable black plastic sheets?

Finding answers to these and other snow questions can lead to a variety of intriguing science projects for those who reside in or who visit snow country.