Melting Snow and Ice After a Freezing Period: A Comprehensive Guide to Weather and Environmental Factors

This article explores the factors that influence the melting of snow and ice, particularly after a period of snow or ice storm followed by freezing temperatures. Understanding these factors is crucial for predicting when and under what conditions melting might occur.

Understanding the Melting Process

Melting snow and ice involves several key factors, including temperature, sunlight, wind, and the type of surface on which the snow or ice is resting. Each of these factors plays a critical role in determining the rate and extent of melting.

Temperature

The most critical factor in melting snow and ice is the temperature. Snow and ice will only begin to melt when the temperature reaches above freezing (32°F or 0°C). If the temperature remains consistently below freezing, melting will not occur, no matter how sunny the weather is. Any melting that does occur can quickly refreeze once the sun sets, or if there are fluctuations in temperature.

Sunlight

Direct sunlight can help to warm the surface of the snow or ice, even if the air temperature is below freezing. This can lead to some melting at the surface, especially on sunny days. However, if the air temperature is consistently below freezing, any melted water may refreeze. The intensity and duration of sunlight are significant factors in the melting process.

Wind

Wind can both enhance and hinder the melting process. Warm winds can increase evaporation, which can help to melt the snow or ice more quickly. However, cold winds can create a wind chill effect, which can slow down the melting process. In general, the most favorable conditions for melting are warm, still days with plenty of direct sunlight.

Surface Type

The type of surface on which the snow or ice is resting can significantly impact the melting process. Darker surfaces, such as asphalt or concrete, absorb more heat from the sun and can lead to faster melting. In contrast, lighter surfaces, such as grass or snow-covered ground, reflect more sunlight and can slow down the melting process. The slope and orientation of the ground can also affect the melting rate, with steeper slopes generally experiencing faster melting due to increased exposure to solar energy.

Melting Snow and Ice: A Deep Dive into Snow Hydrology Models

For a more detailed analysis, we can delve into the principles of snow hydrology models. These models help us understand the processes that govern the transformation of snow into liquid water, taking into account various environmental factors.

Assume that a snow-covered area experiences a period of freezing temperatures followed by sunshine. We can simplify the scenario by assuming a level plane and no further snowfall. We will use Celsius (C) as our temperature scale for simplicity.

A vertical column of snow layers is considered, with a fixed area cross-section of 1 square meter (m2). The mass of the snow, air, and any water vapor present in the column is denoted as M. The temperature at the top of the snow layer is assumed to be 0°C, consistent with the freezing point of water. Below this layer, the temperature and the state of the snow may have varied, but for the sake of simplicity, we will assume a constant temperature of 0°C throughout the column.

The first step in the melting process is the rise in temperature from the surrounding air, ground, and sunlight. These sources of heat will gradually warm the ice in the snow towards 0°C. At this point, the latent heat of melting must absorb approximately 80 calories per cubic centimeter (cal/cc) of ice. This is a simplified assumption, as it does not account for the presence of air within the snow layer.

Over time, the spaces between the dendrites of snow crystals will start to fill with more water vapor and a small amount of liquid water from the existing humidity. This process will cause some of the ice to reach its melting point, even if the overall temperature of the snow pack remains below freezing.

As the snow pack becomes “ripe,” the non-water air will escape, and the density of the snow pack will approach that of liquid water (1.0 g/cm3) but will not quite reach it. Once the snow pack is ripe, the melting process will begin in earnest, and runoff will start to occur. Some of this runoff will turn to vapor as it is heated to the boiling point at 100°C. The energy required to reach this boiling point is approximately 5 times that needed to melt the same volume of ice, and then an additional 700 cal/cc is needed to change the liquid water from 0°C to 100°C.

The entire process of melting, raising the temperature from 0°C to 100°C, and then vaporizing the liquid water can take several days, depending on the specific circumstances and environmental factors. For example, in spring, when the ground is still frozen and the sun is lower in the sky, the process may be slowed down. However, in an area like California, knowing when and how much snow ripens can have significant economic implications, as it affects water availability and management.

Conclusion

Under the conditions described, significant melting is unlikely to occur, even with sunny weather, if the temperature remains below freezing. Any melting that does occur can quickly refreeze once the sun sets or if there are fluctuations in temperature. Therefore, it could take several days or even longer for the snow and ice to melt completely, depending on the specific circumstances and environmental factors.