Snow: the resistance of the snowpack and the influence on the microclimate

Winter is a season characterized by lower temperatures and snow, which can be influenced by the duration of the snow cover. The duration of the latter may vary depending on the geographical region in which it is located. The way in which the presence of snowpack affects the microclimate of a place depends on various factors such as hours of sunshine, air temperature, relative humidity, atmospheric conditions, and others. A constant cover of snow increases the albedo, thereby reducing solar radiation and cooling the earth’s surface temperatures. Conversely, lack of snow causes global warming.

Furthermore, the phenomenon can affect trees in different ways: if the duration of the canopy is long enough to avoid periods of deep frost without extending the spring growing season too much, the trees will benefit from the thicker moss cover underneath. On the other hand, in areas where this balance is not generally achieved, trees can be negatively affected by the effects of more extreme weather events (such as heat waves or frosts). Consequently, we will study the various factors that influence the duration of the snow cover and how it affects the climate.

How the duration of the snowpack orients the microclimate

The presence of a snow cover has a significant impact on the microclimate. One of the main reasons is that it changes the amount of solar energy that is reflected from the ground. Because of its higher albedo, snow reflects more than 75% of incident solar energy, significantly reducing surface irradiance . This can have important consequences for the surface climate in general. Furthermore, the layer of snow on the ground can affect temperatures as it absorbs some short- and medium-range waves, thus preventing solar energy from being converted into heat.

And again, the coat also retains evapotranspiration humidity during the night, preventing it from evaporating the following day. Therefore, due to its ability to conserve moisture, it helps to maintain fairly low levels of humidity and evapotranspiration during dry periods. Finally, snow cover can reduce summer maximum temperatures by absorbing some of the rayleigh (long infrared) energy from the earth’s surface in order to prevent excessive warming during the summer.

The conditioning factors

The duration of the snowpack is influenced by a combination of atmospheric and climatic factors. It depends on many elements such as:

• the quantity and intensity of the arrival of new snow;
• the force of the wind;
• air humidity;
• the temperature of the air and the ground;
• the presence of thermal inversions (a condition in which temperatures increase as one climbs in altitude);
• sun exposure;
• precipitation (rain or hail);
• the type of terrain. 

Furthermore, the greater or lesser snow cover can also be changed by human land use. Exposure to the sun is an important factor influencing the duration of snow as it causes it to melt. Solar radiation can be reduced due to meteorological phenomena such as, for example, low density clouds or low atmospheric pressure , while when solar radiation is high or is prolonged over time, there is usually a rapid melting of the snowpack. If there is no rainfall following the initial formation of the snowpack, it will tend to undergo erosion due to atmospheric agents such as intense winds or hail. Both phenomena can contribute to the rapid melting of the snow cover.

Terrain features

The terrain surrounding a snowy area is critical for monitoring the duration and consistency of the snowpack . Often, people don’t think about how terrain might impact how long the snow lasts, but it actually has a lot to do with it. Soil type can influence soil surface temperature, amount of light received, and moisture retention, all of which are important factors in understanding how snow forms and how long it lasts. The topography of the landit can also affect how many areas are susceptible to snow accumulation and erosion by water or wind. Knowing all the characteristics of the terrain around a mountain area is essential for predicting the extent and duration of snowfall in that region.

The lower limit of the snowfall

The lower limit of the snowfall is another of the important factors determining the duration and the influence of the snowpack on the temperature parameters. Typically, the lower snowline drops during the heaviest precipitation phases , thus causing an increase in snow accumulation.

However, this limit is not fixed in all weather situations. In some cases the limit may be influenced by other processes such as, for example, updrafts produced by the wind or by thermal convection, which cause the snow to evaporate before it reaches the ground. The temperature of the surfaces around the area also affects the duration of the snow cover: in fact, the greater the amount of heat available in that area, the lower the tendency for ice to form on the ground.