Search

1 to 10 of 26
Sort by

Glossary
Surface Temperature

The temperature of a ground surface (e.g. black top, concrete, grass) at a specific time and location. #WeatherTerms


Glossary
Temperature

A measure of the coldness or warmth at a specific time and location expressed in either Fahrenheit (F) or Celsius (C) degrees. #WeatherTerms


Glossary
Snow

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...


Glossary
Slush

Wet snow with a water content in excess of 30%. It has no compressive strength but can refreeze, creating a hazardous condition. #WeatherTerms


Glossary
Sleet

Frozen raindrops. Sleet occurs when rain falls through a deep enough layer of the atmosphere to freeze before reaching the ground surface. It can occur when surface temperatures are either above or below freezing; and unlike freezing rain, sleet hits the ground as frozen ice pellets that can...


Glossary
Road Weather Information Systems (RWIS)

A system that comprises automatic weather stations (referred to as environmental sensor stations) in the field; a communication system for data transfer; and central systems to collect field data from numerous stations. These stations measure real-time atmospheric and pavement temperatures,...


Glossary
Relative Humidity

The amount of water vapor in the air relative to what it could hold at a given temperature. #WeatherTerms


Glossary
Effects of Mechanical Agitation

The hardening process that occurs by breaking up the layers and particles of snow is accelerated by mechanical agitation, which occurs either from wind action causing drifting snow or plowing. This effect has very practical implications in snow management. For example, the time and effort in...


Glossary
Snow Age Hardening

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...


Glossary
Temperature Instability

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...