Wet snow with a water content in excess of 30%. It has no compressive strength but can refreeze, creating a hazardous condition. #WeatherTerms
Precipitation in the form of ice crystals. It originates in clouds when temperatures are below the freezing point, when water vapor in the atmosphere condenses directly into ice without going through the liquid stage. Once an ice crystal has formed, it absorbs and freezes additional water vapor...
A measure of the coldness or warmth at a specific time and location expressed in either Fahrenheit (F) or Celsius (C) degrees. #WeatherTerms
The temperature of a ground surface (e.g. black top, concrete, grass) at a specific time and location. #WeatherTerms
The attraction of dissimilar materials (e.g., snow and pavement). New, dry snow falling on cold, dry pavement will not adhere (bond) strongly. As the temperature rises above about 20º F (-7º C), the amount of liquid surrounding the snow grains increases. This increases the adhesion of the snow...
Refers to the snow’s resistance to collapse or penetration. Snow hardness depends on the grain structure and temperature. The grain structure depends on the snow density and extent of bonding between adjacent grains. Snow hardness can be determined by measuring the resistance to penetration. ...
Temperature Instability affects the amount of liquid coating the snow particles, which in turn influences compressibility , hardness , density and cohesiveness . This characteristic is probably the most important factor affecting its properties, and thus the most important factor affecting...
Another consequence of Temperature Instability of snow is its change in structure with time. An undisturbed snow mass will densify (decrease in volume) and increase in hardness and compressive strength. The snow crystals will then grow, causing the bond strength between crystals to drop...
A measure of the amount of snow in a given volume or space. When the volume of the constant mass of snow decreases, the density increases; that is, the same amount of snow occupies a smaller volume. Undisturbed snow has a lower density than snow compacted by plowing, vehicle tires, or ice....
Cohesion refers to the attraction between similar materials and the ability of the grains to interconnect. Fresh cold, dry snow lacks cohesion because it lacks intergranular contacts. As snow ages, the number of grain contacts increases, and thus, cohesion increases. The compressive strength of...