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A snow roller is a rare meteorological phenomenon in which large snowballs are formed naturally as chunks of snow are blown along the ground by wind, picking up material along the way, in much the same way that the large snowballs used in snowmen are made. They can be as small as a tennis ball, but they can also be bigger than a car.Most snow rollers are a few inches/centimeters wide.
A snowball is a spherical object made from snow, usually created by scooping snow with the hands, and compacting it into a roughly fist-sized ball. The snowball is often used to engage in games, such as snowball fights. Snowball fights are usually light-hearted and involve throwing snowballs at one's friends or family. The pressure exerted by the hands on the snow is a determinant for the final result. Reduced pressure leads to a light and soft snowball. Compacting humid or "packing" snow by applying a high pressure produces a harder snowball, sometimes called an ice ball, which can injure an opponent during a snowball fight.
Wind is the flow of gases on a large scale. On the surface of the Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the Sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space. Winds are commonly classified by their spatial scale, their speed, the types of forces that cause them, the regions in which they occur, and their effect. The strongest observed winds on a planet in the Solar System occur on Neptune and Saturn. Winds have various aspects, an important one being its velocity ; another the density of the gas involved; another its energy content or wind energy. Wind is also a great source of transportation for seeds and small birds; with time things can travel thousands of miles in the wind.
Alternative names for snow rollers include: snow bales,snow donuts, snownuts and wind snowballs. Unlike snowballs made by people, snow rollers are typically cylindrical in shape, and are often hollow since the inner layers, which are the first layers to form, are weak and thin compared to the outer layers and can easily be blown away, leaving what looks like a doughnut or Swiss roll.
A doughnut or donut is a type of fried dough confection or dessert food. The doughnut is popular in many countries and prepared in various forms as a sweet snack that can be homemade or purchased in bakeries, supermarkets, food stalls, and franchised specialty vendors.
A Swiss roll, jelly roll, roll cake, or cream roll is a type of sponge cake roll filled with whipped cream, jam, or icing.
The following conditions are needed for snow rollers to form:
The melting point of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa.
Because of this last condition, snow rollers are more common in hilly areas.However, the precise nature of the conditions required makes them a very rare phenomenon.
The term snow roller also applies to a horse-drawn implement used in the mid to late 19th century (though tractor-drawn examples are still in limited use today, mainly at ski resorts) to pack snow.[ citation needed ] It was mainly used in areas with high snow accumulation for access for horses and horse-drawn sleighs or wagons equipped with skis or runners. The implement was essentially, a large, very wide, wooden wheel, weighed down with stone or concrete.
The Krkonoše, Karkonosze, Riesengebirge (German), Riesageberge or Giant Mountains, are a mountain range located in the north of the Czech Republic and the south-west of Poland, part of the Sudetes mountain system. The Czech-Polish border, which divides the historic regions of Bohemia and Silesia, runs along the main ridge. The highest peak, Sněžka, is the Czech Republic's highest point with an elevation of 1,603 metres (5,259 ft).
Poland, officially the Republic of Poland, is a country located in Central Europe. It is divided into 16 administrative subdivisions, covering an area of 312,696 square kilometres (120,733 sq mi), and has a largely temperate seasonal climate. With a population of approximately 38.5 million people, Poland is the sixth most populous member state of the European Union. Poland's capital and largest metropolis is Warsaw. Other major cities include Kraków, Łódź, Wrocław, Poznań, Gdańsk, and Szczecin.
Pennsylvania, officially the Commonwealth of Pennsylvania, is a state located in the northeastern and Mid-Atlantic regions of the United States. The Appalachian Mountains run through its middle. The Commonwealth is bordered by Delaware to the southeast, Maryland to the south, West Virginia to the southwest, Ohio to the west, Lake Erie and the Canadian province of Ontario to the northwest, New York to the north, and New Jersey to the east.
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.
An avalanche is a cohesive slab of snow lying upon a weaker layer of snow when the snowpack that fractures and slides down a steep slope when triggered. Avalanches are typically triggered in a starting zone from a mechanical failure in the snowpack when the forces of the snow exceed its strength but sometimes only with gradual widening. After initiation, avalanches usually accelerate rapidly and grow in mass and volume as they entrain more snow. If 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.
A sled, sledge, or sleigh is a land vehicle that slides across the surface, usually of ice or snow. It is built with either a smooth underside or a separate body supported by two or more smooth, relatively narrow, longitudinal runners similar in principle to skis. This reduces the amount of friction, which helps to carry heavy loads.
A ski resort is a resort developed for skiing, snowboarding, and other winter sports. In Europe, most ski resorts are towns or villages in or adjacent to a ski area – a mountainous area with pistes and a ski lift system. In North America, it is more common for ski areas to exist well away from towns, so ski resorts usually are destination resorts, often purpose-built and self-contained, where skiing is the main activity.
Wind shear, sometimes referred to as wind gradient, is a difference in wind speed and/or direction over a relatively short distance in the atmosphere. Atmospheric wind shear is normally described as either vertical or horizontal wind shear. Vertical wind shear is a change in wind speed or direction with change in altitude. Horizontal wind shear is a change in wind speed with change in lateral position for a given altitude.
Goggles, or safety glasses, are forms of protective eyewear that usually enclose or protect the area surrounding the eye in order to prevent particulates, water or chemicals from striking the eyes. They are used in chemistry laboratories and in woodworking. They are often used in snow sports as well, and in swimming. Goggles are often worn when using power tools such as drills or chainsaws to prevent flying particles from damaging the eyes. Many types of goggles are available as prescription goggles for those with vision problems.
Randy's Donuts is a bakery and landmark building in Inglewood, California, near Los Angeles International Airport, in a style that dates to a period in the early 20th century that saw a proliferation of programmatic architecture throughout Southern California. This style had its heyday from the mid-1920s to the mid-1930s. By the 1950s however, the trend of designing structures in the shape of the product sold there had changed to focus on signs rather than architecture itself. Randy's is represented by a giant doughnut on the roof of an otherwise ordinary drive-in that is a dedicated doughnut bakery. The building was designed by Henry J. Goodwin.
Ski wax is a material applied to the bottom of snow runners, including skis, snowboards, and toboggans, to improve their coefficient of friction performance under varying snow conditions. The two main types of wax used on skis are glide waxes and grip waxes. They address kinetic friction—to be minimized with a glide wax—and static friction—to be achieved with a grip wax. Both types of wax are designed to be matched with the varying properties of snow, including crystal type and size, and moisture content of the snow surface, which vary with temperature and the temperature history of the snow. Glide wax is selected to minimize sliding friction for both alpine and cross-country skiing. Grip wax provides on-snow traction for cross-country skiers, as they stride forward using classic technique.
A snow fort or snow castle is a usually open-topped temporary structure made of snow walls that is usually used for recreational purposes. Snow forts are generally built by children as a playground game or winter pastime and are used as defensive structures in snowball fights. They are also built and used for make-believe games such as "house", "store", or "community", a game where multiple forts are built in a group. Along with the snowman, it is one of the two structures commonly built by children out of snow.
Firn is partially compacted névé, a type of snow that has been left over from past seasons and has been recrystallized into a substance denser than névé. It is ice that is at an intermediate stage between snow and glacial ice. Firn has the appearance of wet sugar, but has a hardness that makes it extremely resistant to shovelling. Its density generally ranges from 0.4 g/cm³ to 0.83 g/cm³, and it can often be found underneath the snow that accumulates at the head of a glacier.
A doughnut or donut is a manoeuvre performed while driving a vehicle. Performing this manoeuvre entails rotating the rear or front of the vehicle around the opposite set of wheels in a continuous motion, creating (ideally) a circular skid-mark pattern of rubber on a carriageway and possibly even causing the tyres to emit smoke from friction. The move was first done as a race celebration by Alex Zanardi after the 1997 Long Beach Grand Prix, where he performed the manoeuvre as a way to give back to the Long Beach fans and the atmosphere they produced for the teams and racers. He continued to use it as a form of celebration throughout his racing career. The move has now become the post-race celebration of choice for many victorious drivers.
Snow grooming is the process of manipulating snow for recreational uses with a tractor, snowmobile, piste caterpillar, truck or snowcat towing specialized equipment. The process is used to maintain ski hills, cross country ski trails and snowmobile trails by grooming the snow on them. A snow groomer is usually employed to pack snow and improve skiing and snowboarding and snowmobile trail conditions. The resulting pattern on the snow is known as corduroy, and is widely regarded as a good surface on which to ski or ride. Snow groomers can also move accumulated snow made by snow machines as part of a process, called "snow farming".
Architectural glass is glass that is used as a building material. It is most typically used as transparent glazing material in the building envelope, including windows in the external walls. Glass is also used for internal partitions and as an architectural feature. When used in buildings, glass is often of a safety type, which include reinforced, toughened and laminated glasses.
Plastics extrusion is a high-volume manufacturing process in which raw plastic is melted and formed into a continuous profile. Extrusion produces items such as pipe/tubing, weatherstripping, fencing, deck railings, window frames, plastic films and sheeting, thermoplastic coatings, and wire insulation.
Classifications of snow describe and categorize the attributes of snow-generating weather events, including the individual crystals both in the air and on the ground, and the deposited snow pack as it changes over time. Snow can be classified by describing the weather event that is producing it, the shape of its ice crystals or flakes, how it collects on the ground, and thereafter how it changes form and composition. Depending on the status of the snow in the air or on the ground, a different classification applies.
A steam devil is a small, weak whirlwind over water that has drawn fog into the vortex, thus rendering it visible.
A die in polymer processing is a metal restrictor or channel capable of providing a constant cross sectional profile to a stream of liquid polymer. This allows for continuous processing of shapes such as sheets, films, pipes, rods, and other more complex profiles. This is a continuous process, allowing for constant production, as opposed to a sequential (non-constant) process such as injection molding.
This glossary of meteorology is a list of terms and concepts relevant to meteorology and the atmospheric sciences, their sub-disciplines, and related fields.
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