There are many names for the various weather sayings and proverbs that have been created over hundreds, even thousands of years, each attempting to distill some observable aspect of the weather into a memorable phrase, often – though not always – with a catchy rhyme.
This type of oral transfer of knowledge and information would have been essential before reading and writing skills spread to the general populace during the 19th and 20th centuries. Yet even today, various tidbits of information continue to be passed down. I remember as a young boy my parents remarking “it’s too cold to snow.” This didn’t require any investigation, nor was there any attempt to equate this with scientific details as to why this would be. It simply was.
The keys to most weather sayings are observation and experience. I expect most of us have experienced winter’s deep cold when thermometers tumble to the 20s and 30s below zero. Generally, this comes with blue skies by day and starry or moonlit skies at night. When it snows, by contrast, temperatures warm, leading to another phrase, “warming means storming.” But let’s not get off track. Observation and experience tell us that when it’s very cold, it doesn’t snow. So back to the heart of the matter – can it be too cold to snow?
Perhaps a logical place to start would be, why does it snow? It has to be cold enough, essentially 32 degrees or colder. Also necessary is an adequate amount of moisture, known specifically as water vapor. When moisture increases to a point that the air is saturated, the extra moisture turns into very tiny water droplets called cloud droplets. Any additional moisture, when temperatures are below 32 degrees, finds microscopic particles of dust, smoke, sea salt, and even pollen, adding up to a collection of ice that we know as a snow crystal, made famous by Vermont’s own Wilson “Snowflake” Bentley. As moisture increases, the snow crystal production increases, often resulting in dozens of crystals sticking together to form larger snowflakes that descend in the billions with every snowstorm.
Moisture turns out to be the critical factor in snow, though the amount of water vapor greatly depends on the temperature. The tiniest particles of water, water molecules, seem to be rather free-spirited, or expressed more scientifically, as the temperature increases, a water molecule’s energy increases. It vibrates and moves without connecting with other water molecules, which are also “on the move.” As the temperature increases, this more energetic water vapor can increase without connecting to form cloud droplets or raindrops and snowflakes. When the temperature decreases, any water vapor has far less energy, which directly limits the amount of water vapor that can exist in the air at a given temperature. Most important to our discussion, while the water vapor – moisture – decreases, it does not go down to zero. The differences are quite remarkable, as you can see in this abbreviated table above.
In other words, our atmosphere’s capacity for water vapor is more than 20 times greater at 20 degrees, compared to 40 below zero.
Connecting this to the real world, the Fairbanks Museum weather records demonstrate a strong relationship between cold and (lack of) precipitation. First, in looking at the ten coldest Januarys on our records, eight of them featured drier-than-average conditions, one was average, and just one was above average. Changing our viewpoint to look at the ten driest Januarys, nine out of 10 were colder than average. Three of the years made both top-ten lists: 1970, 1981, and 2004.
Deep, arctic cold conditions have their origins over the unforgiving landscape of Siberia, as well as the Yukon region of Alaska and northwest Canada. With virtually no sunlight, should a stagnant area of high pressure with light winds remain over these areas for any length of time, what meager “heat” exists near the Earth’s surface escapes through our atmosphere and out into space. This bitter cold air is also very dense, and at some point begins a southward trek into Canada and then the U.S., delivering a frigid spell of weather. Consider, then, that these arctic outposts experience far colder weather than we do. Using the basic ideas we’ve discussed regarding temperature and moisture, it shouldn’t surprise you that snowfall in these areas is quite low, far less snow than we receive during most winters. I’ve included a map of Canada, [figure 1] showing that the arctic region averages less than 25 inches of snow each year, and only 25 to 50 inches a bit farther south through the Canadian tundra. Compare that to our area, [figure 2], where the lower elevations in Caledonia County see 75 to 100 inches each year (specifically 88 inches at the Fairbanks Museum), while the higher terrain of western and northern Caledonia County regularly gets over 100 inches. One of our reporting stations, Sutton, at 1500 feet in elevation, averages 145 inches.
Although you could be technical and stick to the scientific facts that it is never “too cold” to snow, the time-tested adage demonstrates its accuracy nearly every January when the Winter Warlock sets up his frigid throne in our icy, snowy neighbor.
Mark Breen is the senior meteorologist at the Fairbanks Museum and Planetarium, and for over 30 years he has been the morning voice of weather on several local radio stations, as well as Vermont Public Radio’s an “Eye on the Sky.”
