75-593: Alpine skiing , or downhill skiing , is the pastime of sliding down snow -covered slopes on skis with fixed-heel bindings , unlike other types of skiing ( cross-country , Telemark , or ski jumping ), which use skis with free-heel bindings. Whether for recreation or for sport , it is typically practiced at ski resorts , which provide such services as ski lifts , artificial snow making , snow grooming , restaurants, and ski patrol . " Off-piste " skiers—those skiing outside ski area boundaries—may employ snowmobiles , helicopters or snowcats to deliver them to
150-633: A glacier may form. Otherwise, snow typically melts seasonally, causing runoff into streams and rivers and recharging groundwater . Major snow-prone areas include the polar regions , the northernmost half of the Northern Hemisphere and mountainous regions worldwide with sufficient moisture and cold temperatures. In the Southern Hemisphere , snow is confined primarily to mountainous areas, apart from Antarctica . Snow affects such human activities as transportation : creating
225-401: A rainband ), when temperature is near freezing at the surface. The strong convection that develops has enough moisture to produce whiteout conditions at places which the line passes over as the wind causes intense blowing snow. This type of snowsquall generally lasts less than 30 minutes at any point along its path, but the motion of the line can cover large distances. Frontal squalls may form
300-433: A cirque (corrie or cwm), a typically armchair-shaped geological feature, which collects snow and where the snowpack compacts under the weight of successive layers of accumulating snow, forming névé. Further crushing of the individual snow crystals and reduction of entrapped air in the snow turns it into glacial ice. This glacial ice will fill the cirque until it overflows through a geological weakness or an escape route, such as
375-649: A crystal morphology diagram, relating crystal shapes to the temperature and moisture conditions under which they formed, which is summarized in the following table. Dendrites Hollow prisms Needles Solid plates Dendrites Solid plates Prisms Nakaya discovered that the shape is also a function of whether the prevalent moisture is above or below saturation. Forms below the saturation line tend more toward solid and compact while crystals formed in supersaturated air tend more toward lacy, delicate, and ornate. Many more complex growth patterns also form, which include side-planes, bullet-rosettes, and planar types, depending on
450-447: A droplet has frozen, it grows in the supersaturated environment—one where air is saturated with respect to ice when the temperature is below the freezing point. The droplet then grows by diffusion of water molecules in the air (vapor) onto the ice crystal surface where they are collected. Because water droplets are so much more numerous than the ice crystals, the crystals are able to grow to hundreds of micrometers or millimeters in size at
525-589: A few molecules in the droplet need to get together by chance to form an arrangement similar to that in an ice lattice. The droplet freezes around this "nucleus". In warmer clouds, an aerosol particle or "ice nucleus" must be present in (or in contact with) the droplet to act as a nucleus. Ice nuclei are very rare compared to cloud condensation nuclei on which liquid droplets form. Clays, desert dust, and biological particles can be nuclei. Artificial nuclei include particles of silver iodide and dry ice , and these are used to stimulate precipitation in cloud seeding . Once
600-408: A hard plastic/resin shell with inner padding. Modern ski helmets may include many additional features such as vents, earmuffs, headphones, goggle mounts, and camera mounts. The protective gear used in alpine skiing includes: helmets, mouth guards, shin guards, chin guards, arm guards, back protectors, pole guards, and padding. Mouth guards can reduce the effects of a concussion and protect the teeth of
675-568: A hemisphere's fall , winter, and spring, the atmosphere over continents can be cold enough through the depth of the troposphere to cause snowfall. In the Northern Hemisphere, the northern side of the low-pressure area produces the most snow. For the southern mid-latitudes , the side of a cyclone that produces the most snow is the southern side. A cold front , the leading edge of a cooler mass of air, can produce frontal snowsqualls —an intense frontal convective line (similar to
750-485: A highly porous, sintered material made up of a continuous ice structure and a continuously connected pore space, forming together the snow microstructure". Almost always near its melting temperature, a snowpack is continually transforming these properties wherein all three phases of water may coexist, including liquid water partially filling the pore space. After deposition, snow progresses on one of two paths that determine its fate, either by ablation (mostly by melting) from
825-470: A larger weather system. The physics of snow crystal development in clouds results from a complex set of variables that include moisture content and temperatures. The resulting shapes of the falling and fallen crystals can be classified into a number of basic shapes and combinations thereof. Occasionally, some plate-like, dendritic and stellar-shaped snowflakes can form under clear sky with a very cold temperature inversion present. Snow clouds usually occur in
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#1732783459574900-435: A minimum extent of 2 million square kilometres (0.77 × 10 ^ sq mi) each August to a maximum extent of 45 million square kilometres (17 × 10 ^ sq mi) each January or nearly half of the land surface in that hemisphere. A study of Northern Hemisphere snow cover extent for the period 1972–2006 suggests a reduction of 0.5 million square kilometres (0.19 × 10 ^ sq mi) over
975-530: A mountain range results in adiabatic cooling, and ultimately condensation and precipitation. Moisture is gradually removed from the air by this process, leaving drier and warmer air on the descending, or leeward , side. The resulting enhanced snowfall, along with the decrease in temperature with elevation, combine to increase snow depth and seasonal persistence of snowpack in snow-prone areas. Mountain waves have also been found to help enhance precipitation amounts downwind of mountain ranges by enhancing
1050-399: A normal downhill ski which would most likely sink into the snow. Freestyle skis are used by skiers who ski terrain parks. These skis are meant to help a skier who skis jumps, rails, and other features placed throughout the terrain park. Freestyle skis are usually fully symmetric, meaning they are the same dimensions from the tip of the ski to the backside (tail) of the ski. All-mountain skis are
1125-488: A series of snow events, punctuated by freezing and thawing, over areas that are cold enough to retain snow seasonally or perennially. Major snow-prone areas include the Arctic and Antarctic , the Northern Hemisphere, and alpine regions. The liquid equivalent of snowfall may be evaluated using a snow gauge or with a standard rain gauge , adjusted for winter by removal of a funnel and inner cylinder. Both types of gauges melt
1200-409: A short distance ahead of the surface cold front or behind the cold front where there may be a deepening low-pressure system or a series of trough lines which act similar to a traditional cold frontal passage. In situations where squalls develop post-frontally, it is not unusual to have two or three linear squall bands pass in rapid succession separated only by 25 miles (40 kilometers), with each passing
1275-419: A snow fall or seasonal snowpack, or by transitioning from firn (multi-year snow) into glacier ice . Over the course of time, a snowpack may settle under its own weight until its density is approximately 30% of water. Increases in density above this initial compression occur primarily by melting and refreezing, caused by temperatures above freezing or by direct solar radiation. In colder climates, snow lies on
1350-608: A snowpack can create flow fingers and ponding or flow along capillary barriers, which can refreeze into horizontal and vertical solid ice formations within the snowpack. Among the measurements of the properties of snowpacks that the International Classification for Seasonal Snow on the Ground includes are: snow height, snow water equivalent, snow strength, and extent of snow cover. Each has a designation with code and detailed description. The classification extends
1425-416: A snowslide or snowslip) is a rapid flow of snow down a sloping surface. Avalanches are typically triggered in a starting zone from a mechanical failure in the snowpack (slab avalanche) when the forces on the snow exceed its strength but sometimes only with gradually widening (loose snow avalanche). After initiation, avalanches usually accelerate rapidly and grow in mass and volume as they entrain more snow. If
1500-630: A substance denser than névé , yet less dense and hard than glacial ice . Firn resembles caked sugar and is very resistant to shovelling. Its density generally ranges from 550 to 830 kilograms per cubic metre (34 to 52 lb/cu ft), and it can often be found underneath the snow that accumulates at the head of a glacier . The minimum altitude that firn accumulates on a glacier is called the firn limit , firn line or snowline . There are four main mechanisms for movement of deposited snow: drifting of unsintered snow, avalanches of accumulated snow on steep slopes, snowmelt during thaw conditions, and
1575-472: Is "the transformation that the snow undergoes in the period from deposition to either melting or passage to glacial ice". Starting as a powdery deposition, snow becomes more granular when it begins to compact under its own weight, be blown by the wind, sinter particles together and commence the cycle of melting and refreezing. Water vapor plays a role as it deposits ice crystals, known as hoar frost , during cold, still conditions. During this transition, snow "is
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#17327834595741650-401: Is a device used to connect the skier's boot to the ski. The purpose of the binding is to allow the skier to stay connected to the ski, but if the skier falls the binding can safely release them from the ski to prevent injury. There are two types of bindings: the heel and toe system (step-in) and the plate system binding. Ski boots are one of the most important accessories to skiing. They connect
1725-466: Is from Norwegian dialects slalåm meaning a trail ( låm ) on a slope ( sla ). In Telemark in the 1800s, the steeper and more difficult trails were called ville låmir (wild trails). Skiing competitions in Telemark often began on a steep mountain, continued along a logging-slides ( tømmerslepe ) and was completed with a sharp turn ( Telemark turn ) on a field or frozen lake. This type of competition used
1800-446: Is made of plastic and contains the buckles. Most ski boots contain a strap at shin level to allow for extra strength when tightening the boots. Ski poles, one in each hand, are used for balance and propulsion. Ski helmets reduce the chances of head injury while skiing. Ski helmets also help to provide warmth to the head since they incorporate an inner liner that traps warmth. Helmets are available in many styles, and typically consist of
1875-438: Is measured by percent slope, not degree angle. A 100% slope is a 45-degree angle. In general, beginner slopes (green circle) are between 6% and 25%. Intermediate slopes (blue square) are between 25% and 40%. Difficult slopes (black diamond) are 40% and up. Although slope gradient is the primary consideration in assigning a trail difficulty rating, other factors come into play. A trail will be rated by its most difficult part, even if
1950-429: Is not a requirement, as blowing snow can create a ground blizzard . Snowstorm intensity may be categorized by visibility and depth of accumulation. Snowfall's intensity is determined by visibility , as follows: Snowsqualls may deposit snow in bands that extend from bodies of water as lake-event weather or result from the passage of an upper-level front. The International Classification for Seasonal Snow on
2025-429: Is rotated onto its edge, the pattern cut into its side causes it to bend into an arc. The contact between the arc of the ski edges and the snow naturally causes the ski to tend to move along that arc, changing the skiers direction of motion. This is an advanced form of speed control by increasing the pressure on one inside edge (for example the right ski), then releasing the pressure and shifting immediately to increasing
2100-464: Is termed ocean-effect or bay-effect snow . The effect is enhanced when the moving air mass is uplifted by the orographic influence of higher elevations on the downwind shores. This uplifting can produce narrow but very intense bands of precipitation which may deposit at a rate of many inches of snow each hour, often resulting in a large amount of total snowfall. The areas affected by lake-effect snow are called snowbelts . These include areas east of
2175-404: Is the stem, angling the tail of the ski off to the side, while the tips remain close together. In doing so, the snow resists passage of the stemmed ski, creating a force that retards downhill speed and sustains a turn in the opposite direction. When both skis are stemmed, there is no net turning force, only retardation of downhill speed. Carving is based on the shape of the ski itself; when the ski
2250-645: The Great Lakes , the west coasts of northern Japan, the Kamchatka Peninsula in Russia, and areas near the Great Salt Lake , Black Sea , Caspian Sea , Baltic Sea , and parts of the northern Atlantic Ocean. Orographic or relief snowfall is created when moist air is forced up the windward side of mountain ranges by a large-scale wind flow. The lifting of moist air up the side of
2325-806: The World Championships , and the Winter Olympics . Broadly speaking, competitive skiing is divided into two disciplines: Other disciplines administered by the FIS but not usually considered part of alpine are speed skiing and grass skiing . The triple crown of alpine skiing consists of winning all three World Cup titles in one season or all three Gold medals at the Winter Olympic Games in Slalom , Giant slalom , and Downhill skiing events. Only two people have ever accomplished
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2400-552: The atmosphere —usually within clouds—and then fall, accumulating on the ground where they undergo further changes. It consists of frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size, precipitate and accumulate on surfaces, then metamorphose in place, and ultimately melt, slide or sublimate away. Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in
2475-411: The movement of glaciers after snow has persisted for multiple years and metamorphosed into glacier ice. When powdery snow drifts with the wind from the location where it originally fell, forming deposits with a depth of several meters in isolated locations. After attaching to hillsides, blown snow can evolve into a snow slab, which is an avalanche hazard on steep slopes. An avalanche (also called
2550-460: The stem christie in Christiania (Oslo) in 1868, the technique was originally called christiania turn (norwegian: christianiasving or kristianiasving ) after the city (first printed in 1901 in guidelines for ski jumping). The telemark turn was the alternative technique. The christiania turn later developed into parallel turn as the standard technique in alpine skiing. The term "slalom"
2625-741: The 103 ski resorts in the Northeastern United States operating in 2012 may not be able to maintain an economically viable ski season by 2050. In Europe, half of the glacial ice in the Alps has melted and the European Geosciences Union projects snowpack in the mountains could decline 70 percent by 2100 (however, if humans manage to keep global warming below 2 °C, the snow-cover reduction would be limited to 30 percent by 2100). Snow Snow comprises individual ice crystals that grow while suspended in
2700-648: The 35-year period. The following are world records regarding snowfall and snowflakes: The cities (more than 100,000 inhabitants) with the highest annual snowfall are Aomori (792 cm), Sapporo (485 cm) and Toyama (363 cm) in Japan , followed by St. John's (332 cm) and Quebec City (315 cm) in Canada , and Syracuse, NY (325 cm). According to the International Association of Cryospheric Sciences, snow metamorphism
2775-460: The Ground defines "height of new snow" as the depth of freshly fallen snow, in centimeters as measured with a ruler, that accumulated on a snowboard during an observation period of 24 hours, or other observation interval. After the measurement, the snow is cleared from the board and the board is placed flush with the snow surface to provide an accurate measurement at the end of the next interval. Melting, compacting, blowing and drifting contribute to
2850-413: The accumulated snow and report the amount of water collected. At some automatic weather stations an ultrasonic snow depth sensor may be used to augment the precipitation gauge. Snow flurry , snow shower , snow storm and blizzard describe snow events of progressively greater duration and intensity. A blizzard is a weather condition involving snow and has varying definitions in different parts of
2925-481: The athlete. Shin guards, pole guards, arm guards and chin guards are mainly used in slalom skiing in order to protect the body parts having impact with the gates. Back protectors and padding, also known as stealth, is worn for giant slalom and other speed events in order to better protect the body if an athlete were to have an accident at high speeds. Elite competitive skiers participate in the FIS World Cup ,
3000-425: The atmosphere by attracting supercooled water droplets, which freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles, columns and rime . As snow accumulates into a snowpack , it may blow into drifts. Over time, accumulated snow metamorphoses, by sintering , sublimation and freeze-thaw . Where the climate is cold enough for year-to-year accumulation,
3075-458: The avalanche moves fast enough some of the snow may mix with the air forming a powder snow avalanche, which is a type of gravity current . They occur in three major mechanisms: Many rivers originating in mountainous or high-latitude regions receive a significant portion of their flow from snowmelt. This often makes the river's flow highly seasonal resulting in periodic flooding during the spring months and at least in dry mountainous regions like
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3150-406: The bindings to be more closely matched to the fit of the boot, and offer improved performance. The new plastic model contained two parts of the boots: an inner boot and an outer shell. The inner part of the boot (also called the liner) is the cushioning part of the boot and contains a footbed along with a cushion to keep a skier's foot warm and comfortable. The outer shell is the part of the boot that
3225-448: The conditions and ice nuclei. If a crystal has started forming in a column growth regime at around −5 °C (23 °F) and then falls into the warmer plate-like regime, plate or dendritic crystals sprout at the end of the column, producing so called "capped columns". Magono and Lee devised a classification of freshly formed snow crystals that includes 80 distinct shapes. They documented each with micrographs. Snow accumulates from
3300-475: The context of larger weather systems, the most important of which is the low-pressure area, which typically incorporate warm and cold fronts as part of their circulation. Two additional and locally productive sources of snow are lake-effect (also sea-effect) storms and elevation effects, especially in mountains. Mid-latitude cyclones are low-pressure areas which are capable of producing anything from cloudiness and mild snow storms to heavy blizzards . During
3375-544: The contribution of snowmelt to river hydraulics and ground hydrology . In doing so, they employ a variety of instruments to observe and measure the phenomena studied. Their findings contribute to knowledge applied by engineers , who adapt vehicles and structures to snow, by agronomists , who address the availability of snowmelt to agriculture , and those, who design equipment for sporting activities on snow. Scientists develop and others employ snow classification systems that describe its physical properties at scales ranging from
3450-450: The crystal facets and hollows/imperfections mean that the crystals often appear white in color due to diffuse reflection of the whole spectrum of light by the small ice particles. Micrography of thousands of snowflakes from 1885 onward, starting with Wilson Alwyn Bentley , revealed the wide diversity of snowflakes within a classifiable set of patterns. Closely matching snow crystals have been observed. Ukichiro Nakaya developed
3525-446: The difficulty of measuring snowfall. Glaciers with their permanent snowpacks cover about 10% of the earth's surface, while seasonal snow covers about nine percent, mostly in the Northern Hemisphere, where seasonal snow covers about 40 million square kilometres (15 × 10 ^ sq mi), according to a 1987 estimate. A 2007 estimate of snow cover over the Northern Hemisphere suggested that, on average, snow cover ranges from
3600-483: The expense of the water droplets by the Wegener–Bergeron–Findeisen process . These large crystals are an efficient source of precipitation, since they fall through the atmosphere due to their mass, and may collide and stick together in clusters, or aggregates. These aggregates are snowflakes , and are usually the type of ice particle that falls to the ground. Although the ice is clear, scattering of light by
3675-431: The fall line without gaining speed. The snowplough turn is the simplest form of turning and is usually learned by beginners. To perform the snowplough turn one must be in the snowplough position while going down the ski slope. While doing this they apply more pressure to the inside of the opposite foot of which the direction they would like to turn. This type of turn allows the skier to keep a controlled speed and introduces
3750-417: The fall line, across the hill instead of down it, will accelerate more slowly. The speed of descent down any given hill can be controlled by changing the angle of motion in relation to the fall line, skiing across the hill rather than down it. Downhill skiing technique focuses on the use of turns to smoothly turn the skis from one direction to another. Additionally, the skier can use the same techniques to turn
3825-610: The feat: In most ski resorts, the runs are graded according to comparative difficulty so that skiers can select appropriate routes. The grading schemes around the world are related, although with significant regional variations. A beginner-rated trail at a large mountain may be more of an intermediate-rated trail on a smaller mountain. In the United States and Canada, there are four rating symbols: Easy (green circle), Intermediate (blue square), and Difficult (black diamond), and Experts Only (double black diamond) Ski trail difficulty
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#17327834595743900-442: The gap between two mountains. When the mass of snow and ice is sufficiently thick, it begins to move due to a combination of surface slope, gravity and pressure. On steeper slopes, this can occur with as little as 15 m (49 ft) of snow-ice. Scientists study snow at a wide variety of scales that include the physics of chemical bonds and clouds ; the distribution, accumulation, metamorphosis, and ablation of snowpacks; and
3975-453: The ground all winter. By late spring, snow densities typically reach a maximum of 50% of water. Snow that persists into summer evolves into névé , granular snow, which has been partially melted, refrozen and compacted. Névé has a minimum density of 500 kilograms per cubic metre (31 lb/cu ft), which is roughly half of the density of liquid water. Firn is snow that has persisted for multiple years and has been recrystallized into
4050-413: The idea of turning across the fall line. Modern alpine skis are shaped to enable carve turning, and have evolved significantly since the 1980s, with variants including powder skis, freestyle skis, all-mountain skis, and children's skis. Powder skis are usually used when there is a large amount of fresh snow; the shape of a powder ski is wide, allowing the ski to float on top of the snow, compared to
4125-445: The individual crystal to the aggregated snowpack. A sub-specialty is avalanches , which are of concern to engineers and outdoors sports people, alike. Snow science addresses how snow forms, its distribution, and processes affecting how snowpacks change over time. Scientists improve storm forecasting, study global snow cover and its effect on climate, glaciers, and water supplies around the world. The study includes physical properties of
4200-462: The knee, head, neck and shoulder area, hands and back. Ski helmets are highly recommended by professionals as well as doctors. Head injuries caused in skiing can lead to death or permanent brain damage. In alpine skiing, for every 1000 people skiing in a day, on average between two and four will require medical attention. Most accidents are the result of user error leading to an isolated fall. Learning how to fall correctly and safely can reduce
4275-615: The lift needed for condensation and precipitation. A snowflake consists of roughly 10 water molecules which are added to its core at different rates and in different patterns depending on the changing temperature and humidity within the atmosphere that the snowflake falls through on its way to the ground. As a result, snowflakes differ from each other though they follow similar patterns. Snow crystals form when tiny supercooled cloud droplets (about 10 μm in diameter) freeze . These droplets are able to remain liquid at temperatures lower than −18 °C (0 °F), because to freeze,
4350-563: The material as it changes, bulk properties of in-place snow packs, and the aggregate properties of regions with snow cover. In doing so, they employ on-the-ground physical measurement techniques to establish ground truth and remote sensing techniques to develop understanding of snow-related processes over large areas. In the field snow scientists often excavate a snow pit within which to make basic measurements and observations. Observations can describe features caused by wind, water percolation, or snow unloading from trees. Water percolation into
4425-414: The most common type of ski, and tend to be used as a typical alpine ski. All-mountain skis are built to do a little bit of everything; they can be used in fresh snow ( powder ) or used when skiing groomed runs. Slalom race skis, usually referred to as race skis, are short, narrow skis, which tend to be stiffer because they are meant for those who want to go fast as well as make quick sharp turns. The binding
4500-502: The mountain West of the US or most of Iran and Afghanistan , very low flow for the rest of the year. In contrast, if much of the melt is from glaciated or nearly glaciated areas, the melt continues through the warm season, with peak flows occurring in mid to late summer. Glaciers form where the accumulation of snow and ice exceeds ablation. The area in which an alpine glacier forms is called
4575-489: The natural and typical terrain in Telemark. Some races were on "bumpy courses" ( kneikelåm ) and sometimes included "steep jumps" ( sprøytehopp ) for difficulty. The first known slalom competitions were presumably held in Telemark around 1870 in conjunction with ski jumping competitions, involving the same athletes and on slopes next to the ski jump. Husebyrennet from 1886 included svingrenn (turning competition on hills),
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#17327834595744650-409: The need for keeping roadways, wings, and windows clear; agriculture : providing water to crops and safeguarding livestock; sports such as skiing , snowboarding , and snowmachine travel; and warfare . Snow affects ecosystems , as well, by providing an insulating layer during winter under which plants and animals are able to survive the cold. Snow develops in clouds that themselves are part of
4725-428: The other inside edge (the left ski). Then repeat if necessary. Each increased pressure slows the speed. Alternating right and left allows the skis to remain parallel and point ahead without turning. The increase and release sequence results in the up and down motions of the upper body. Some skiers go down the top of moguls and control the speed by checking at the tops. This is how they can practically go straight down
4800-454: The rest of the trail is easy. Ski resorts assign ratings to their own trails, rating a trail compared only with other trails at that resort. Also considered are width of the trail, sharpest turns, terrain roughness, and whether the resort regularly grooms the trail. In 2014, there were more than 114,000 alpine skiing-related injuries treated in hospitals, doctor's offices, and emergency rooms. The most common types of ski injuries are those of
4875-464: The risk of injury. According to a 2004 Harvard Medical School study, alpine skiing burns between 360 and 532 calories per hour. Winter season lengths are projected to decline at ski areas across North America and Europe due to the effects of global warming . In the United States, winter season lengths are projected to decline by more than 50 percent by 2050 and by 80 percent by 2090 if greenhouse gas emissions continue at current rates. About half of
4950-401: The same point roughly 30 minutes apart. In cases where there is a large amount of vertical growth and mixing, the squall may develop embedded cumulonimbus clouds resulting in lightning and thunder which is dubbed thundersnow . A warm front can produce snow for a period as warm, moist air overrides below-freezing air and creates precipitation at the boundary. Often, snow transitions to rain in
5025-430: The ski away from the direction of movement, generating skidding forces between the skis and snow which further slow the descent. Good technique results in a fluid flowing motion from one descent angle to another one, adjusting the angle as needed to match changes in the steepness of the run. This looks more like a single series of S's than turns followed by straight sections. The oldest and still common type of turn on skis
5100-399: The skier to the skis, allowing them full control over the ski. When ski boots first came about they were made of leather and laces were used. The leather ski boots started off as low-cut, but gradually became taller, allowing for more ankle support, as injuries became more common . Eventually the tied laces were replaced with buckles and the leather boots were replaced with plastic. This allowed
5175-526: The term slalåm had not been introduced at that time. Slalom was first used at a skiing competition in Sonnenberg in 1906. Two to three decades later, the sport spread to the rest of Europe and the US. The first slalom ski competition occurred in Mürren , Switzerland in 1922. A skier following the fall line will reach the maximum possible speed for that slope. A skier with skis pointed perpendicular to
5250-1089: The top of a slope. Back-country skiers may use specialized equipment with a free-heel mode, including 'sticky' skins on the bottoms of the skis to stop them sliding backwards during an ascent, then locking the heel and removing the skins for their descent. Alpine ski racing has been held at the Winter Olympics since 1936 . A competition corresponding to modern slalom was introduced in Norway at Oslo in 1886. As of 2023, there were estimated to be 55 million people worldwide who engaged in alpine skiing. The estimated number of skiers, who practiced alpine, cross-country skiing , and related snow sports, amounted to 30 million in Europe, 20 million in North America, and 14 million in Japan. As of 1996, there were reportedly 4,500 ski areas, operating 26,000 ski lifts and enjoying skier visits. The predominant region for downhill skiing
5325-406: The warm sector behind the front. Lake-effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water, warming the lower layer of air which picks up water vapor from the lake, rises up through the colder air above, freezes, and is deposited on the leeward (downwind) shores. The same effect occurring over bodies of salt water
5400-412: The winter when they froze over. Skiing was an integral part of transportation in colder countries for thousands of years. In the 1760s, skiing was recorded as being used in military training. The Norwegian army held skill competitions involving skiing down slopes, around trees and obstacles while shooting. The birth of modern alpine skiing is often dated to the 1850s, and during the late 19th century, skiing
5475-551: The world. In the United States , a blizzard occurs when two conditions are met for a period of three hours or more: a sustained wind or frequent gusts to 35 miles per hour (16 m/s), and sufficient snow in the air to reduce visibility to less than 0.4 kilometers (0.25 mi). In Canada and the United Kingdom , the criteria are similar. While heavy snowfall often occurs during blizzard conditions, falling snow
5550-458: Was Europe, followed by Japan and the US. The ancient origins of skiing can be traced back to prehistoric times in Russia, Finland, Sweden and Norway where varying sizes and shapes of wooden planks were found preserved in peat bogs . The word ski is related to the Old Norse word skíð , which means "split piece of wood or firewood." Skis were first invented to cross wetlands and marshes in
5625-554: Was adapted from a method of transportation to a competitive and recreational sport. Norwegian legend Sondre Norheim first began the trend of skis with curved sides, and bindings with stiff heel bands made of willow . Norheim also trended the slalom turn style. The wooden skis designed by Norheim closely resemble the shape of modern slalom skis. Norheim was the champion of the first downhill skiing competition, reportedly held in Oslo, Norway in 1868. Norheim impressed spectators when he used
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