Snow routinely affects civilization in four major areas: transportation, agriculture, structures, and sports. Most transportation modes are impeded by snow on the travel surface. Agriculture often relies on snow as a source of seasonal moisture. Structures may fail under snow loads. Humans find a wide variety of recreational activities in snowy landscapes. It also affects the conduct of warfare. The
Federal Highway Administration Manual of Practice for an Effective Anti-icing Program emphasizes "anti-icing" procedures that prevent the bonding of snow and ice to the road. Key aspects of the practice include: understanding anti-icing in light of the level of service to be achieved on a given roadway, the climatic conditions to be encountered, and the different roles of deicing, anti-icing, and abrasive materials and applications, and employing anti-icing "toolboxes", one for operations, one for decision-making and another for personnel. The elements to the toolboxes are: •
Operations – Addresses the application of solid and liquid chemicals, using various techniques, including prewetting of chloride-salts. It also addresses plowing capability, including types of snowplows and blades used. •
Decision-making – Combines weather forecast information with road information to assess the upcoming needs for application of assets and the evaluation of treatment effectiveness with operations underway. •
Personnel – Addresses training and deployment of staff to effectively execute the anti-icing program, using the appropriate materials, equipment and procedures. The manual offers matrices that address different types of snow and the rate of snowfall to tailor applications appropriately and efficiently.
Snow fences, constructed upwind of roadways control snow drifting by causing windblown, drifting snow to accumulate in a desired place. They are also used on railways. Additionally, farmers and ranchers use snow fences to create drifts in basins for a ready supply of water in the spring.
Aviation In order to keep airports open during winter storms, runways and taxiways require snow removal. Unlike roadways, where chloride chemical treatment is common to prevent snow from bonding to the pavement surface, such chemicals are typically banned from airports because of their strong corrosive effect on aluminum aircraft. Consequently, mechanical brushes are often used to complement the action of snow plows. Given the width of runways on airfields that handle large aircraft, vehicles with large plow blades, an echelon of plow vehicles or
rotary snowplows are used to clear snow on runways and taxiways. Terminal aprons may require or more to be cleared. Properly equipped aircraft are able to fly through snowstorms under
instrument flight rules. Prior to takeoff, they require
deicing fluid during snowstorms to prevent accumulation and freezing of snow and other precipitation on wings and fuselages, which may compromise the safety of the aircraft and its occupants. In flight, aircraft rely on a variety of mechanisms to avoid rime and other types of icing in clouds, these include pulsing
pneumatic boots, electro-thermal areas that generate heat, and fluid deicers that bleed onto the surface.
Rail Railroads have traditionally employed two types of snow plows for clearing track: the
wedge plow, which casts snow to both sides, and the
rotary snowplow, which is suited for addressing heavy snowfall and casting snow far to one side or the other. Prior to the invention of the rotary snowplow ca. 1865, it required multiple
locomotives to drive a wedge plow through deep snow. After clearing the track with such plows, a "flanger" is used to clear snow from between the rails that are below the reach of the other types of plows. Where icing may affect the steel-to-steel contact of locomotive wheels on track, abrasives (typically sand) have been used to provide traction on steeper uphills. Railroads employ
snow sheds—structures that cover the track—to prevent the accumulation of heavy snow or avalanches to cover tracks in snowy mountainous areas, such as the
Alps and the
Rocky Mountains. File:TowPLow front view2.JPG|Trucks plowing snow on a highway in
Missouri File:Winter Operations @ Brussels Airport January 2013 (8387468508).jpg|Airport snow-clearing operations include plowing and brushing File:RhB ABe 8-12 Allegra mit Spurpflug bei Ospizio Bernina.jpg|Swiss low-profile, train-mounted snowplow
Construction Snow can be compacted to form a
snow road and be part of a
winter road route for vehicles to access isolated communities or construction projects during the winter. Snow can also be used to provide the supporting structure and surface for a runway, as with the
Phoenix Airfield in Antarctica. The snow-compacted runway is designed to withstand approximately 60 wheeled flights of heavy-lift military aircraft a year.
Agriculture , showing snow in the mountain ranges—including the Himalayas—which feed the Indus river and its tributaries, and agricultural areas in eastern
Pakistan and northwestern
India that draw on them for irrigation. Snowfall can be beneficial to agriculture by serving as a
thermal insulator, conserving the heat of the Earth and protecting
crops from subfreezing weather. Some agricultural areas depend on an accumulation of snow during winter that will melt gradually in spring, providing water for crop growth, both directly and via runoff through streams and rivers, which supply irrigation canals. the
Indus River and
its tributaries, which rise in
Tibet and the western Himalayas and provide irrigation water to northern and eastern
Pakistan and northwestern India from rapidly retreating glaciers, and the
Colorado River, which receives much of its water from seasonal snowpack in the
Rocky Mountains and provides irrigation water to some .
Structures Snow is an important consideration for loads on structures. To address these, European countries employ
Eurocode 1: Actions on structures - Part 1-3: General actions - Snow loads. In North America, ASCE
Minimum Design Loads for Buildings and Other Structures gives guidance on snow loads. Both standards employ methods that translate maximum expected ground snow loads onto design loads for roofs. Ice dams may result in
damaged building materials or in damage or injury when the ice dam falls off or from attempts to remove ice dams. The melting results from heat passing through the roof under the highly insulating layer of snow.
Utility lines In areas with trees, utility distribution lines on poles are less susceptible to snow loads than they are subject to damage from trees falling on them, felled by heavy, wet snow. Elsewhere, snow can accrete on power lines as "sleeves" of rime ice. Engineers design for such loads, which are measured in kg/m (lb/ft) and power companies have forecasting systems that anticipate types of weather that may cause such accretions. Rime ice may be removed manually or by creating a sufficient short circuit in the affected segment of power lines to melt the accretions.
Sports and recreation Snow figures into many winter sports and forms of recreation, including
skiing and
sledding. Common examples include
cross-country skiing,
Alpine skiing,
snowboarding,
snowshoeing, and
snowmobiling. The design of the equipment used, e.g. skis and snowboards, typically relies on the bearing strength of snow and contends with the
coefficient of friction bearing on snow. Skiing is by far the largest form of winter recreation. As of 1994, of the estimated 65–75 million skiers worldwide, there were approximately 55 million who engaged in
Alpine skiing, the rest engaged in
cross-country skiing. Approximately 30 million skiers (of all kinds) were in Europe, 15 million in the US, and 14 million in Japan. As of 1996, there were reportedly 4,500 ski areas, operating 26,000 ski lifts and enjoying 390 million skier visits per year. The preponderant region for downhill skiing was Europe, followed by Japan and the US. Increasingly, ski resorts are relying on
snowmaking, the production of snow by forcing water and pressurized air through a
snow gun on ski slopes. Snowmaking is mainly used to supplement natural snow at
ski resorts. This allows them to improve the reliability of their snow cover and to extend their ski seasons from late autumn to early spring. The production of snow requires low temperatures. The threshold temperature for snowmaking increases as humidity decreases.
Wet-bulb temperature is used as a metric since it takes air temperature and relative humidity into account. Snowmaking is a relatively expensive process in its energy consumption, thereby limiting its use.
Ski wax enhances the ability of a ski (or other runner) to slide over snow by reducing its coefficient of friction, which depends on both the properties of the snow and the ski to result in an optimum amount of lubrication from melting the snow by friction with the ski—too little and the ski interacts with solid snow crystals, too much and capillary attraction of meltwater retards the ski. Before a ski can slide, it must overcome the maximum value static friction. Kinetic (or dynamic) friction occurs when the ski is moving over the snow. Noted
winter warfare campaigns where snow and other factors affected the operations include: • The
French invasion of Russia, where poor traction conditions for ill-shod horses made it difficult for supply wagons to keep up with troops. That campaign was also strongly affected by cold, whereby the retreating army reached
Neman River in December 1812 with only 10,000 of the 420,000 that had set out to invade
Russia in June of the same year. • The
Winter War, an attempt by the
Soviet Union to take territory in
Finland in late 1939 demonstrated superior winter tactics of the
Finnish Army, regarding over-snow mobility,
camouflage, and use of the terrain. • The
Battle of the Bulge, a German counteroffensive during
World War II, starting December 16, 1944, was marked by heavy snowstorms that hampered allied air support for ground troops, but also impaired German attempts to supply their front lines. On the Eastern Front with the Nazi invasion of Russia in 1941,
Operation Barbarossa, both Russian and German soldiers had to endure terrible conditions during the
Russian winter. While use of
ski infantry was common in the Red Army, Germany formed only
one division for movement on skis. notably during the
Battle of Chosin Reservoir, which was a stark example of cold affecting military operations, especially vehicles and weapons. File:Night Bivouac of Great Army.jpg|Bivouac of
Napoleon's
Grande Armée, during the winter retreat from
Moscow File:Finn ski troops.jpg|Finnish ski troops during the invasion of
Finland by the
Soviet Union File:Army vehicles on a road in Belgium.jpg|Army vehicles coping with snow during the
Battle of the Bulge of
World War II File:Cold Response DV dag.jpg|Norwegian military preparations during the 2009
Cold Response exercise File:Navy Seals Winter warfare at Mammoth Mountain, California, in December 2014.jpg|
United States Navy SEALs training for winter warfare at
Mammoth Mountain,
California ==Effects on plants and animals==