When considering the impacts of snow, the first thing you think of is not likely warming. For the near surface soil, the impact is often warming as illustrated by today's featured chart. The chart presents a time series of soil temperature at depth from an ISU Soil Moisture Network site near Ames. While this chart does not present snow information, the impact of the introduction of snow cover last week is readily apparent with the immediate cessation of temperature variability. How can it be that soil temperatures warmed with frozen snow over top the ground? Snow cover acts like a blanket to prevent most soil heat from escaping into the air, so warmth at deeper depths is able to warm shallower depths. The chart does show cooling though on the 14th when bitterly cold air temperatures allowed the snow to drop in temperature as well, which overwhelmed any positive warming that was previously happening when the snow was at a higher (but still below freezing temperature). The slightly warmer air temperatures on Wednesday can be seen at the tail end of this plot as again, snow temperatures warmed as well. The presence of snow cover is critical during periods of extreme cold air temperatures in Iowa as plants, pathogens, and other soil residents that perhaps are killed at extreme cold temperatures are saved by the mitigating impacts of the snow cover.

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Tags:   snowcover   soil