We have entered the micro-season of “The Spring Water Holds Warmth”, which is the second part of the mini season of Minor Cold.
Minor Cold, which will be followed by the mini season Major Cold, is the fifth of the six mini seasons of winter. The micro-seasons contained within this mini season are:
- The Water Dropwort Flourishes (Jan 06 – Jan10)
- The Spring Water Holds Warmth (Jan 11 0 Jan 15)
- The Pheasant First Calls (Jan 16 – Jan 20)
The micro-seasons were established in 1685 by Japanese astronomer Shibuka Shunkai. Each micro-season lasts about five days and highlights a slight change in the natural environment. The micro-seasons are specific to the climate of Japan as they were developed around their agrarian society. However, just because the calendar focuses on Japan doesn’t mean that it isn’t applicable to others. They can become a starting point for a personal exploration into the world around you.
The Spring Water Holds Warmth
As a young person growing up in the Northeast, January was usually the time that we started thinking about ice fishing and pond hockey. As we started sharpening our skates for the season, we were also reminded of the dangers of thin ice. This micro-season, “Spring Water Holds Warmth”, could be seen as a reminder about the variable factors that play into ice thickness.
The general rule of thumb is to stay off ice that is less than 4 inches thick. The only good way to know the thickness of ice is to drill several test holes and measure it. With that said, there is a formula that can be used to estimate the freezing rate of ice.
Calculating Freezing Degree Days.
Much like calculating out wind chill factors, there is a formula that you can use to determine the rate at which the ice accumulates on a pond or lake. You begin by calculating the average temperature of the day by adding low temperature and high temperature and dividing by 2. (Use degrees Fahrenheit.) Now subtract that average from 32 degrees, the temperature at which water freezes. You have now just calculated what they call “freezing degree days.”
Freezing degree days will add 1 inch of ice for every 15 freezing degree days in a 24 hour period. The only caveat to this formula is that there must be a thin layer of ice on the surface before this formula works.
Mike Szydlowski, Columbia Public Schools’ Science Coordinator, provides us with a narrative of how this works.
“If the low temperature today was 24 degrees and the high was 30 degrees, the average temperature of the day was 27 degrees. Subtract that from 32, and you get 5 freezing degree days for this day. . . . If we had a day with 5 freezing degree days, you would use the formula 5/15 = .33. On this day you would add .33 inches of ice, or 1/3 of an inch. But remember, this is after the first layer of ice forms.” (1)
For those who are more visual learners, The graph below provides another representation of how this formula works.
It should be remembered that there are a lot of variables that come into ice formation. So these formulas and graphs should only be used as a way to estimate thickness. You should always test the ice before you go out on it and physically measure the thickness to determine its safety. Another important caveat to this formula is that it is only for lakes and ponds. In other words, it is just for water that is relatively still.
So how might spring water, or moving water, play into this formula?
Does spring water freeze?
An interesting thing about spring water is that it is moving water. As a result, it doesn’t necessarily freeze over at the same time as pond or lake water. The scientist at UC Santa Barbara explain this process by stating;
‘For flowing water to freeze, the surrounding air has to be colder than 32°F, because the flowing water mixes with itself. So, the colder water on the surface mixes with the warmer water from the bottom, and the average temperature is somewhere between the two. . . Also, the motion of the water can cause heating. For example, water in a waterfall gains kinetic energy as it falls, which is converted into heat and sound energy at the bottom. Therefore, the surrounding air temperature would have to be lower to force the water in the waterfall to cool to 32°F and freeze.”(2)
Another thing to consider is that spring water emerges from below ground where it is warmer than the surface temperatures. In Vermont, where the winters are fairly cold, the frost line is estimated to be 5 feet down. What that means is that once you get below 5 feet in the ground, the ground temperature stays above freezing. So when we think about spring water holding its warmth, we are perhaps talking about how the spring water is resistant to freezing because it emerges from below the frost line.
Although, this warmer water can slow down the freezing process, it will not completely prevent it. It just takes many days of really cold temperatures for this water to freeze over. Also, because rivers and springs don’t freeze at the same consistency as ponds or lakes, care should always be taken when walking on frozen rivers and other places with moving water.
Some Haiku About This Season
And, because we can’t close a post without some poetry. I have found a few haiku about ice.
this ice tastes bitter – enough for a rat to wet his throat -Matsuo Basho
Little pieces of ice in the moonlight Snow, thousands of em -Jack Kerouac
Water in the birdbath - a film of ice On the moon -Kerouac
America: fishing licenses the license To meditate -Kerouac
This last haiku by Kerouac isn’t necessarily about ice. But when I think about fishing, I tend to think about ice fishing.
You can read more poetry about snow and ice here.
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