Alpine skiing evolved from cross-country skiing when ski lift infrastructure was developed at mountain resorts to tow skiers back to the top of slopes, thus making it possible to repeatedly enjoy skiing down steep, long slopes that would be otherwise tiring to climb. The sport is popular wherever the combination of snow, mountain slopes, and a sufficient tourist infrastructure can be built up, including parts of Europe, North America, Australia and New Zealand, the South America Andes, and East Asia.
As skiers gain confidence, they may tackle steeper, longer and more uneven slopes (including off-piste and ungroomed runs) at higher speeds. In North America, the easiest ski runs are marked by green circles, and are typically fairly flat and smooth. Sometimes known as "bunny slopes", they are usually groomed by specially equipped snowcats every night. A blue square marks slopes of medium difficulty; these blue squares may be steeper or narrower than green circles, or they may be left in a natural state rather than machine-groomed. A black diamond run is yet steeper than a blue square and often involves challenging terrain such as moguls, narrow passes, unmarked obstacles, double fall lines, or gladed sections. A double black diamond is for experts only; these trails are steep, rarely groomed and often left in a completely natural state. There is no standard for these designations, however, and each ski resort determines them relative to their own terrain difficulty. So, for instance, a blue-square (mid-level) trail at one ski mountain may be markedly more difficult than a black-diamond (expert) trail at another mountain. In Europe the system is based on colour alone. North American green circles, blue squares, black diamonds, and double blacks correspond to European green, blue, red, and black trails, respectively.
Different snow and weather conditions, such as dry air in low temperatures or spring conditions, or icy crust, or fresh powder require different skiing techniques and equipment.
Racing involves making fast turns around gates in an attempt to attain the fastest overall time down one or two runs of a race course. Elite competitive skiers participate in the annual World Cup series, as well as the quadrennial Olympic Games and the biennial World Championships. Slalom (SL), giant slalom (GS), super giant slalom (super-G), and downhill (DH) are the four racing disciplines, with downhill being the fastest event and slalom being the most technical. There is also a "combined" event that includes one downhill run and two slalom runs on a single day. In 2005, the FIS (Fédération Internationale de Ski) introduced a new event to the World Cup calendar called the super combined, or super combi, consisting of one shortened downhill run and just one slalom run. That year, the FIS also introduced an alpine team racing event at the World Championships in Bormio, Italy. Ski racing is controlled by a set of rules which are enforced by FIS. These rules include such things as regulation ski sizes, sidecuts, boot heights, binding risers and many other things which all ensure one particular skier has no advantage over another however these regulations are constantly being pushed by ski manufacturers using new technologies. Next year (2008) these regulations are set to be changed in order to make it harder for racers to complete a race course. Some changes include increasing the minimum ski length and also the sidecut which will make the ski turn less tightly.
Freestyle skiing incorporates events such as moguls, aerials, and sometimes "new-school" events such as halfpipe, big air, slopestyle, and skiercross. Together with extreme skiing, new-school freestyle skiing is also sometimes known as freeskiing. Until relatively recently, freestyle competitions also included an event called ballet, later renamed "acro-ski."
In addition to racing and freestyle, other types of alpine skiing competitions exist. One discipline administered by the FIS but not usually considered part of racing is speed skiing, in which competitors strive to achieve the highest total speed in a straight line, with no gates or turns. Numerous non-FIS competitions have emerged over the years. More traditional events include gelandesprung jumping (ski jumping for distance on alpine equipment), and "powder 8" contests; among the more recent introductions are "big mountain" or "extreme skiing" contests, in which athletes start at the top of a mountain and ski a route down that involves wide, fast turns as well as cliff drops. The competitors are judged on the technical difficulty of their routes and any tricks they perform on the way down the hill.
In the United States, alpine skiing competition is managed by the U.S. Ski and Snowboard Association (USSA). The USSA organizes all levels of skiing competition from grassroots through the U.S. Ski Team and the Olympics.
In North America, a color–shape rating system is used to indicate the difficulty of trails (otherwise known as slopes or pistes). Australian ski slopes also share the same rating system.
There is no governing body that assigns difficulty ratings to ski trails. Instead, ski resorts assign ratings to their own trails, marking a given trail according to its relative difficulty when compared with other trails at that resort. As a result, identically-pitched trails at different resorts can have different ratings. Some skiers and snowboarders may interpret this as manipulation of ratings of their slopes to appeal to as wide an audience as possible; in fact, it is an attempt by ski areas to conform to the trail rating conventions.
Although slope gradient is the primary consideration in assigning a trail rating, other factors come into play — including trail width, normal snow conditions and whether or not the resort regularly grooms the trail.
|Trail Rating||Symbol||Level of difficulty||Description|
|Green circle||Easiest||The easiest pistes at a mountain. Green Circle trails are generally wide and groomed, typically with slope gradients ranging from 6% to 25% (a 100% slope is a 45 degree angle).|
|Blue square||Intermediate||Intermediate difficulty slopes with grades commonly ranging from 25% to 40%. These slopes are usually groomed. Blue Square runs comprise the bulk of pistes at most ski areas, and are usually among the most heavily-trafficked.|
|Black diamond||Difficult||Amongst the most difficult at a given mountain. Black Diamond trails tend to be steep (typically 40% and up) and may or may not be groomed, though the introduction of winch-cats has made the grooming of steep slopes both possible and more frequent.|
|Double black diamond||Expert||These trails are even more difficult than Black Diamond, due to exceptionally steep slopes and other hazards such as narrow trails, exposure to wind, and the presence of obstacles such as steep drop-offs or trees. They are intended only for the most experienced skiers. This trail rating is fairly new; by the 1980s, technological improvements in trail construction and maintenance, coupled with intense marketing competition, led to the creation of a Double Black Diamond rating.|
|Variations||Various||Variations such as doubling a symbol to indicate increased difficulty, or combining two different symbols to indicate intermediate difficulty are occasionally used. One example is a diamond overlapping a square to indicate a trail rating between a Blue Square and a Black Diamond. Mont Tremblant in Canada utilizes two blue squares right next to each other to indicate the same thing. Many resorts in Summit County, Colorado use a double diamond with an "EX" in the center to mark a trail even more difficult than a double diamond. The combination of symbols is comparatively rare at U.S. ski areas; most ski resorts stick to the standard 4-symbol progression.|
|Terrain parks||Various||Terrain parks are whole or portions of trails that can offer a variety of jumps, half-pipes, and other special "extreme" sporting obstacles beyond traditional moguls. The trails are typically represented by an orange rectangle with rounded corners. Usually, the terrain park will carry its own trail rating, indicating the level of challenge. A terrain park with a Black Diamond or Double Black Diamond rating would contain greater and more challenging obstacles than a park with a Blue Square rating.|
Alpine slope classification in Europe is less rigidly tied to slope angle than in North America. A lower angle slope may be classified as more difficult than a steeper slope if, for instance, it is narrower and/or requires better skiing ability to carry speed through flatter sections while controlling speed through sharp hairpin turns, off-camber slope angles or exposed rock.
Japan has more than 1000 ski areas (115 in Nagano Prefecture alone), many of them small and family-oriented, so comparisons between slope classifications in Japan and "equivalent" slopes in Europe or North America are minimal.
Skiers and snowboarders can encounter a wide range of snow and weather conditions, in part due to the location of specific resorts and global weather patterns at the time.
Natural snow ranges in consistency from very light and fluffy to dense and heavy, depending upon atmospheric conditions as it falls. Snow is often measured by moisture content, or the amount of water in a given volume of snow. Some areas of the United States' Rocky Mountains, for example, can receive considerable amounts of snow with moisture content as low as three to five percent; in the Northeastern United States and the Alps, moisture content is more typically 15 percent or more. Snow made by mechanical snowmaking often has moisture content of 35 percent or more.
Temperatures play a critical role in snow moisture content, but other atmospheric conditions are also relevant. Air currents and other factors determine snow crystal shape; obviously, the farther apart given snow crystals are, the more air is contained in the newly settled snow, resulting in lower net moisture content in a given volume of snow. Snow produced mechanically typically has high relative moisture content and low amounts of loft because the crystal structure resembles small, dense pellets.
Even the fluffiest snow has mass, and snow typically settles under its own weight after time. This is one reason why untouched snow measuring 20 cm on the day it falls might be measured at 15 cm the day following. Snow is also subject to sublimation — a process by which water can go directly from a frozen state to a gaseous state without first melting. It is this same process that ultimately makes ice cubes shrink in a freezer.
There are other factors that impact snow beyond its moisture content and crystal shape, however. Snow is impacted by wind, sunlight, skier traffic, ambient air temperature, relative humidity and grooming equipment; all of these factors combine to change snow crystal shape and density over time.
Thus, skiers and snowboarders typically encounter a wide range of snow conditions over the course of a season. Some of the more common conditions include:Powder: Light, fluffy snow, found during and immediately after snowfall. Skiing and snowboarding in deep powder snow is a favorite among skilled, experienced skiers and snowboarders; sometimes known as "powderhounds" hunting for the next big dump. Because Western snow generally has a lower moisture content, western powder is lighter and easier to ski than heavier eastern powder. Utah snow is especially known for being extremely light and dry as well as a lot of snow found in New Zealand.Packed powder: Powder snow that has been compressed, either by means of mechanical snow grooming apparatus or skier traffic. The term can also be used to describe snow that has been properly made with adequate control over snow-making apparatus. This snow condition is favored by beginners and the majority of recreational skiers, in that it tends to be relatively forgiving, easy to turn upon, and requires less skill to negotiate than powder snow.Granular snow: Snow with large crystals, i.e. small pellets. Depending on sun and temperature conditions, it may be wet granular snow — meaning that there is a considerable amount of unfrozen water in it, or loose granular snow, which has no unfrozen water. Wet granular snow will form a snowball; loose granular snow will not. Wet granular conditions are often found in the springtime. Loose granular conditions are generally produced when wet granular snow has re-frozen and then been broken up by snowgrooming apparatus.Corn snow: The result of repeated daily thaws and nightly re-freezing of the surface. Because of the thaw-refreeze cycle, snow crystal shapes change over time, producing crystal shapes somewhat akin to wet granular, but larger. True corn snow is a delight to ski or ride.Ice: Skiers and snowboarders typically regard any snow condition that is very hard as "ice". In fact, true ice conditions are comparatively rare. Much of what is perceived to be ice is actually a frozen granular condition — wet granular snow that has refrozen to form a very dense surface. Telling the difference is comparatively easy; if one can get a ski pole to stand up in it, the surface is likely to be more of a frozen granular surface than an icy one — and while it is certainly not as enjoyable as many other snow conditions, skilled skiers and snowboarders can successfully negotiate it. In fact, ice is a preferred condition among racers, in that the surface tends to be quite fast and race course conditions tend to remain more consistent during the race, with fewer ruts developing on the course. Another form of icy condition can be found at higher elevation resorts in the Rocky Mountains and in Europe; direct sunlight can melt the top layers of snow crystals and subsequent freezing produces a very shiny, slick surface.Crust: A crust condition exists when soft snow is covered by a harder upper layer upon the surface. This crust can be created by freezing rain (precipitation formed in warmer upper levels of the atmosphere, falling into a temperature inversion at which surface temperatures are below freezing, and freezing on contact with the ground), by direct sunlight, and by wind loading which packs down the upper layers of the snowpack but leaves lower layers more or less unaffected. Crusts are extremely challenging conditions.Dust on crust: A trace of new snow on top of crust. Undesirable.Spring conditions: A catch-all term ski areas use to describe conditions when numerous different surface types can be found on the mountain — usually in the later part of the season, although the term is sometimes used during an extended midwinter thaw. The term also generally reflects the presence of bare spots and/or areas of thin cover. With spring conditions, the snow is usually firm in early morning (even reaching frozen granular status if left ungroomed), breaking a softer corn or wet granular surface mid-day, and is often very soft and mushy in afternoon (many skiers refer to this type of snow condition as "mashed potatoes," due to its heaviness). In some instances when the snow is untracked, sun baked, slightly dirty, with the consistency of a snow cone, it is called "tecate powder". The speed with which conditions change on a given spring day is directly related to the exposure of the slope relative to the sun. In the northern hemisphere, east- and south-facing slopes tend to soften first; west-facing slopes generally soften by mid-day. North-facing slopes may hold on to their overnight snow conditions throughout the day.