MOLINE, Ill — The Quad Cities is currently working its way through the second snowiest January on record. No surprise given our string of winter storm systems that rolled through starting on Jan. 8. This snow is beneficial in several ways, including the water that will result from it upon melting. There's more though, and that's the subject of today's question from Charlie A. in Moline, Illinois. "Does snow help keep the ground thawed out?" Let's dig in!
A natural blanket
A blanket of snow can indeed keep the ground warmer in the winter, acting like a natural blanket for the soil. Fresh snow is full of air pockets between snowflakes that act as a barrier, slowing down the transfer of heat from the warm ground to the colder air above.
As we've discussed in Storm Track 8 University, the snow itself is a very poor conductor of heat. It has an extremely high albedo, meaning it reflects a tremendous amount of energy from the sun. Because it holds heat so poorly, it greatly impacts the flow of heat trying to escape from the ground. A thicker snowpack provides better insulation compared to a dusting, with an average of 10-12 inches of snowpack needed for measurable warming effects.
This winter has been a prime example, especially in the last few weeks. As of Jan. 22, the frost depth remains very shallow thanks to the timing of our recent heavy snowfall. The fact that it came in before a significant Arctic blast of air with several days spent with temperatures well below zero has kept the frost very shallow. Something we will be able to take advantage of once all the snow does melt!
Benefits to the ground
It's normal for a certain depth of soil to frost and freeze during the winter in the Quad Cities. However, you don't want an extreme depth to freeze, otherwise, we see adverse impacts to not only plant life but also household plumbing, too! An extremely deep frost depth can rupture water mains and also prevent beneficial moisture from reaching plant roots.
A thick blanket of snow can protect plant life, safeguarding roots and bulbs from frost damage. Also, by slowing down melting, snow helps retain moisture in the soil, giving plants a nice headstart the following spring.
Not all snow is created equal
Snow that has been on the ground for an extended period of time is usually not as efficient at insulating the ground compared to fresh, fluffy snow. When temperatures rise above freezing, the insulating effect often disappears, exposing the ground to colder temperatures again.
All in all, a blanket of snow can definitely be quite beneficial to the soil! It can however also be harmful, especially if it falls while the soil is still mostly unfrozen and sticks around for a while, creating snow mold.
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