1.
Snow
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Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets, 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, a glacier may form, otherwise, snow typically melts seasonally, causing runoff into streams and rivers and recharging groundwater. Major snow-prone areas include the regions, the upper half of the Northern Hemisphere and mountainous regions worldwide with sufficient moisture. In the Southern Hemisphere, snow is confined primarily to mountainous areas, 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 a weather system. The physics of snow crystal development in clouds results from a set of variables that include moisture content. The resulting shapes of the falling and fallen crystals can be classified into a number of shapes and combinations. Occasionally, some plate-like, dendritic and stellar-shaped snowflakes can form under clear sky with a cold temperature inversion present. Two additional and locally productive sources of snow are lake-effect storms and elevation effects, miid-latitude cyclones are low pressure areas which are capable of producing anything from cloudiness and mild snow storms to heavy blizzards. During a hemispheres 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, when temperature is near freezing at the surface. The strong convection that develops has enough moisture to produce whiteout conditions at places which 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, 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, often, snow transitions to rain in the warm sector behind the front. The same effect occurs over bodies of salt water, when it is termed ocean-effect or bay-effect snow. The effect is enhanced when the air mass is uplifted by the orographic influence of higher elevations on the downwind shores
2.
Emergence
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Emergence is central in theories of integrative levels and of complex systems. For instance, the phenomenon of life as studied in biology is an emergent property of chemistry, in philosophy, theories that emphasize emergent properties have been called emergentism. Almost all accounts of emergentism include a form of epistemic or ontological irreducibility to the lower levels, in philosophy, emergence is often understood to be a claim about the etiology of a systems properties. An emergent property of a system, in context, is one that is not a property of any component of that system. Nicolai Hartmann, one of the first modern philosophers to write on emergence and this idea of emergence has been around since at least the time of Aristotle. John Stuart Mill and Julian Huxley are two of many scientists and philosophers who have written on the concept, further, every resultant is clearly traceable in its components, because these are homogeneous and commensurable. The emergent is unlike its components insofar as these are incommensurable, economist Jeffrey Goldstein provided a current definition of emergence in the journal Emergence. Goldstein initially defined emergence as, the arising of novel and coherent structures, patterns, Systems scientist Peter Corning also says that living systems cannot be reduced to underlying laws of physics, Rules, or laws, have no causal efficacy, they do not in fact “generate” anything. They serve merely to describe regularities and consistent relationships in nature and these patterns may be very illuminating and important, but the underlying causal agencies must be separately specified. But that aside, the game of chess illustrates, why any laws or rules of emergence and evolution are insufficient. Even in a game, you cannot use the rules to predict “history” – i. e. the course of any given game. Indeed, you cannot even reliably predict the move in a chess game. Because the “system” involves more than the rules of the game and it also includes the players and their unfolding, moment-by-moment decisions among a very large number of available options at each choice point. The game of chess is inescapably historical, even though it is constrained and shaped by a set of rules. Moreover, and this is a key point, the game of chess is also shaped by teleonomic, cybernetic and it is not simply a self-ordered process, it involves an organized, “purposeful” activity. Usage of the notion emergence may generally be subdivided into two perspectives, that of weak emergence and strong emergence, in terms of physical systems, weak emergence is a type of emergence in which the emergent property is amenable to computer simulation. This is opposed to the notion of strong emergence, in which the emergent property cannot be simulated by a computer. Some common points between the two notions are that emergence concerns new properties produced as the system grows, which is to say ones which are not shared with its components or prior states, also, it is assumed that the properties are supervenient rather than metaphysically primitive
3.
Light
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Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to light, which is visible to the human eye and is responsible for the sense of sight. Visible light is defined as having wavelengths in the range of 400–700 nanometres, or 4.00 × 10−7 to 7.00 × 10−7 m. This wavelength means a range of roughly 430–750 terahertz. The main source of light on Earth is the Sun, sunlight provides the energy that green plants use to create sugars mostly in the form of starches, which release energy into the living things that digest them. This process of photosynthesis provides virtually all the used by living things. Historically, another important source of light for humans has been fire, with the development of electric lights and power systems, electric lighting has effectively replaced firelight. Some species of animals generate their own light, a process called bioluminescence, for example, fireflies use light to locate mates, and vampire squids use it to hide themselves from prey. Visible light, as all types of electromagnetic radiation, is experimentally found to always move at this speed in a vacuum. In physics, the term sometimes refers to electromagnetic radiation of any wavelength. In this sense, gamma rays, X-rays, microwaves and radio waves are also light, like all types of light, visible light is emitted and absorbed in tiny packets called photons and exhibits properties of both waves and particles. This property is referred to as the wave–particle duality, the study of light, known as optics, is an important research area in modern physics. Generally, EM radiation, or EMR, is classified by wavelength into radio, microwave, infrared, the behavior of EMR depends on its wavelength. Higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths, when EMR interacts with single atoms and molecules, its behavior depends on the amount of energy per quantum it carries. There exist animals that are sensitive to various types of infrared, infrared sensing in snakes depends on a kind of natural thermal imaging, in which tiny packets of cellular water are raised in temperature by the infrared radiation. EMR in this range causes molecular vibration and heating effects, which is how these animals detect it, above the range of visible light, ultraviolet light becomes invisible to humans, mostly because it is absorbed by the cornea below 360 nanometers and the internal lens below 400. Furthermore, the rods and cones located in the retina of the eye cannot detect the very short ultraviolet wavelengths and are in fact damaged by ultraviolet. Many animals with eyes that do not require lenses are able to detect ultraviolet, by quantum photon-absorption mechanisms, various sources define visible light as narrowly as 420 to 680 to as broadly as 380 to 800 nm
4.
Dry ice
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Dry ice, sometimes referred to as cardice, is the solid form of carbon dioxide. It is used primarily as a cooling agent and its advantages include lower temperature than that of water ice and not leaving any residue. It is useful for preserving frozen foods where mechanical cooling is unavailable, Dry ice sublimates at −78.5 °C at Earth atmospheric pressures. This extreme cold makes the solid dangerous to handle without protection due to burns caused by freezing, while generally not very toxic, the outgassing from it can cause hypercapnia due to buildup in confined locations. Dry ice is the form of carbon dioxide, a molecule consisting of a single carbon atom bonded to two oxygen atoms. Dry ice is colorless, non-flammable, with a sour zesty odor, at pressures below 5.13 atm and temperatures below −56.4 °C, CO2 changes from a solid to a gas with no intervening liquid form, through a process called sublimation. The opposite process is called deposition, where CO2 changes from the gas to solid phase, at atmospheric pressure, sublimation/deposition occurs at −78.5 °C. The density of dry ice varies, but usually ranges between about 1.4 and 1.6 g/cm3. The low temperature and direct sublimation to a gas makes dry ice an effective coolant, since it is colder than water ice and its enthalpy of sublimation is 571 kJ/kg. Dry ice is non-polar, with a moment of zero. The composition results in low thermal and electrical conductivity and it is generally accepted that dry ice was first observed in 1835 by French inventor Adrien-Jean-Pierre Thilorier, who published the first account of the substance. In his experiments, he noted that when opening the lid of a cylinder containing liquid carbon dioxide. This left only solid dry ice in the container, slate applied for a US patent to sell dry ice commercially. Subsequently, he became the first to make dry ice successful as an industry, in 1925, this solid form of CO2 was trademarked by the DryIce Corporation of America as Dry ice, thus leading to its common name. That same year the DryIce Co. sold the substance commercially for the first time, the alternative name Cardice is a registered trademark of Air Liquide UK Ltd. It is sometimes written as card ice, First, gases with a high concentration of carbon dioxide are produced. Such gases can be a byproduct of another process, such as producing ammonia from nitrogen and natural gas, second, the carbon dioxide-rich gas is pressurized and refrigerated until it liquifies. When this occurs some liquid carbon dioxide vaporizes, causing a lowering of temperature of the remaining liquid
5.
Scanning electron microscope
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A scanning electron microscope is a type of electron microscope that produces images of a sample by scanning it with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography. The electron beam is scanned in a raster scan pattern. SEM can achieve better than 1 nanometer. Specimens can be observed in vacuum, in low vacuum, in wet conditions. The most common SEM mode is detection of electrons emitted by atoms excited by the electron beam. The number of electrons that can be detected depends, among other things. By scanning the sample and collecting the electrons that are emitted using a special detector. An account of the history of SEM has been presented by McMullan. Ardenne applied the principle not only to achieve magnification but also to purposefully eliminate the chromatic aberration otherwise inherent in the electron microscope. He further discussed the various modes, possibilities and theory of SEM. The types of produced by an SEM include secondary electrons, reflected or back-scattered electrons, photons of characteristic X-rays and light, absorbed current. Secondary electron detectors are standard equipment in all SEMs, but it is rare that a machine would have detectors for all other possible signals. The signals result from interactions of the beam with atoms at various depths within the sample. In the most common or standard detection mode, ie secondary electron imaging or SEI, consequently, SEM can produce very high-resolution images of a sample surface, revealing details less than 1 nm in size. Back-scattered electrons are beam electrons that are reflected from the sample by elastic scattering and they emerge from deeper locations within the specimen and consequently the resolution of BSE images is generally poorer than SE images. BSE images can provide information about the distribution of different elements in the sample, characteristic X-rays are emitted when the electron beam removes an inner shell electron from the sample, causing a higher-energy electron to fill the shell and release energy. These characteristic X-rays are used to identify the composition and measure the abundance of elements in the sample, due to the very narrow electron beam, SEM micrographs have a large depth of field yielding a characteristic three-dimensional appearance useful for understanding the surface structure of a sample
6.
Hard rime
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Hard rime is a white ice that forms when the water droplets in fog freeze to the outer surfaces of objects. It is often seen on trees atop mountains and ridges in winter and this fog freezes to the windward side of tree branches, buildings, or any other solid objects, usually with high wind velocities and air temperatures between −2 and −8 °C. Hard rime formations are difficult to shake off, they have an appearance, unlike soft rime, which looks feathery or spiky, or clear ice. Rime ice can accumulate on the edges and control surfaces of aircraft operating in certain meteorological conditions. Rime is also a weather form, meteorologists distinguish between three basic types of ice forming on vertical and horizontal surfaces by deposition of supercooled water droplets. Of course there are also intermediate formations, soft rime is less dense than hard rime and is milky and crystalline, like sugar. Soft rime appears similar to hoar frost, hard rime is somewhat less milky, especially if it is not heavy. Clear ice is transparent and homogeneous and resembles ice-cube ice in appearance and its amorphous, dense structure helps it cling tenaciously to any surface on which it forms. Both rime types are less dense than ice and cling less tenaciously. Glaze ice is similar in appearance to clear ice but it is the result of a different process. These three types occur also when ice forms on the surface of an aircraft when it flies through a cloud made of supercooled water liquid droplets, rime ice is the least dense, milky ice is intermediate and clear ice is the most dense. Dense ice can spoil lift and may have an effect on an airborne aircraft. Under some atmospheric conditions, forming and descending snow crystals may encounter and these droplets, which have a diameter of about 10 µm, can exist in the unfrozen state down to temperatures near −40 °C. Contact between the crystal and the supercooled droplets results in freezing of the liquid droplets onto the surface of the crystals. This process of growth is known as accretion. Crystals that exhibit frozen droplets on their surfaces are referred to as rimed, when this process continues so that the shape of the original snow crystal is no longer identifiable, the resulting crystal is referred to as graupel. However, observations of snow crystals with a scanning electron microscope clearly show cloud droplets measuring up to 50 µm on the surface of the crystals. The rime has been observed on all four forms of snow crystals, including plates, dendrites, columns
7.
Micrometer
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Micrometers are usually, but not always, in the form of calipers, which is why micrometer caliper is another common name. The spindle is a very accurately machined screw and the object to be measured is placed between the spindle and the anvil, the spindle is moved by turning the ratchet knob or thimble until the object to be measured is lightly touched by both the spindle and the anvil. Micrometers are also used in telescopes or microscopes to measure the apparent diameter of celestial bodies or microscopic objects, the micrometer used with a telescope was invented about 1638 by William Gascoigne, an English astronomer. Colloquially the word micrometer is often shortened to mike or mic, the word micrometer is a neoclassical coinage from Greek micros, meaning small, and metron, meaning measure. The Merriam-Webster Collegiate Dictionary says that English got it from French, neither the metre nor the micrometre nor the micrometer as we know them today existed at that time. However, the people of that time did have much need for, and interest in, the word was no doubt coined in reference to this endeavor, even if it did not refer specifically to its present-day senses. In 1844 details of Whitworths workshop micrometer were published and this was described as having a strong frame of cast iron, the opposite ends of which were two highly finished steel cylinders, which traversed longitudinally by action of screws. The ends of the cylinders where they met was of hemispherical shape, one screw was fitted with a wheel graduated to measure to the ten thousandth of an inch. His object was to furnish ordinary mechanics with an instrument which, the micrometer caliper was introduced to the mass market in anglophone countries by Brown & Sharpe in 1867, allowing the penetration of the instruments use into the average machine shop. Brown & Sharpe were inspired by earlier devices, one of them being Palmers design. In 1888 Edward W. Morley added to the precision of micrometric measurements, each type of micrometer caliper can be fitted with specialized anvils and spindle tips for particular measuring tasks. For example, the anvil may be shaped in the form of a segment of screw thread, in the form of a v-block, universal micrometer sets come with interchangeable anvils, such as flat, spherical, spline, disk, blade, point, and knife-edge. The term universal micrometer may also refer to a type of micrometer whose frame has modular components, allowing one micrometer to function as outside mic, depth mic, step mic, blade micrometers have a matching set of narrow tips. They allow, for example, the measuring of a narrow o-ring groove, pitch-diameter micrometers have a matching set of thread-shaped tips for measuring the pitch diameter of screw threads. Limit mics have two anvils and two spindles, and are used like a snap gauge, the part being checked must pass through the first gap and must stop at the second gap in order to be within specification. The two gaps accurately reflect the top and bottom of the tolerance range, bore micrometer, typically a three-anvil head on a micrometer base used to accurately measure inside diameters. Tube micrometers have a cylindrical anvil positioned perpendicularly to a spindle and is used to measure the thickness of tubes. Micrometer stops are micrometer heads that are mounted on the table of a milling machine, bedways of a lathe, or other machine tool
8.
Guinness World Records
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The book itself holds a world record, as the best-selling copyrighted book of all time. As of the 2017 edition, it is now in its 63rd year of publication, the international franchise has extended beyond print to include television series and museums. On 10 November 1951, Sir Hugh Beaver, then the director of the Guinness Breweries, went on a shooting party in the North Slob, by the River Slaney in County Wexford. After missing a shot at a golden plover, he involved in an argument over which was the fastest game bird in Europe. That evening at Castlebridge House, he realised that it was impossible to confirm in reference books whether or not the golden plover was Europes fastest game bird. Beaver knew that there must be numerous other questions debated nightly in pubs throughout Ireland and abroad and he realised then that a book supplying the answers to this sort of question might prove successful. Beavers idea became reality when Guinness employee Christopher Chataway recommended University friends Norris and Ross McWhirter, the twin brothers were commissioned to compile what became The Guinness Book of Records in August 1954. A thousand copies were printed and given away, after the founding of The Guinness Book of Records at 107 Fleet Street, the first 198-page edition was bound on 27 August 1955 and went to the top of the British best seller lists by Christmas. The following year, it launched in the US, and sold 70,000 copies, since then, Guinness World Records has become a household name and the global leader in world records. Because the book became a hit, many further editions were printed, eventually settling into a pattern of one revision a year, published in September/October. The McWhirters continued to compile it for many years, Ross McWhirter was assassinated by the Provisional Irish Republican Army in 1975. Following Ross assassination, the feature in the show where questions about records posed by children were answered was called Norris on the Spot, Guinness Superlatives Limited was formed in 1954 to publish the first book. Sterling Publishing owned the rights to the Guinness book in the US for decades, and, under their management, the group was owned by Guinness PLC and subsequently Diageo until 2001, when it was purchased by Gullane Entertainment. Gullane was itself purchased by HIT Entertainment in 2002, with offices in New York City and Tokyo, Guinness World Records global headquarters remain in London, while its museum attractions are based at Ripley headquarters in Orlando, Florida, US. Recent editions have focused on record feats by person competitors, many records also relate to the youngest person who achieved something, such as the youngest person to visit all nations of the world, being Maurizio Giuliano. Each edition contains a selection of the records from the Guinness database, as well as new records. The majority of records are no longer listed in the book or on the website. For those unable to wait the 4–6 weeks for a reply, the Guinness Book of Records is the worlds most sold copyrighted book, earning it an entry within its own pages
9.
Fort Keogh
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Fort Keogh is a former United States Army post located on the western edge of todays Miles City, Montana. It is situated on the bank of the Yellowstone River. It was originally called Tongue River Cantonment for two years, when relocated 1 mile west in 1878, it was renamed Fort Keogh in honor of Captain Myles Keogh, who died at the Battle of the Little Bighorn. In 1877 the fort became the headquarters for the newly created military district, today the former military post is a United States Department of Agriculture livestock and range research station. It is listed on the National Register of Historic Places, the development of Fort Keogh as a military installation soon stimulated traders to supply the liquor and other service businesses that were the beginning of Miles City. The order for development of the fort was signed on August 28,1876, the Armys intended use for its garrison at the post was to reduce warfare by the American Indians in the region and to persuade them to resettle on reservations. Colonel David S. Stanley had originally scouted the first site of the fort during the Yellowstone Expedition of 1873 and he thought the location would be good for supplying troops throughout the region. But, the Army did not decide to build the fort until after Custers overwhelming defeat at the Battle of the Little Bighorn. As the US and developers planned to bring the Great Northern Railway to the region, the troops came into contact with two tribes of Indians, the Lakota and the Crow. The Sioux had pushed the Crow west of their lands as they moved west. Resentful of the Sioux, the Crow frequently allied with the Army, General Miles established the Cantonment Tongue River at the confluence of the north-flowing Tongue River and the east-flowing Yellowstone River. The site would provide access to boats bringing supplies up the Yellowstone. Miles was a well-respected as a leader, not only by his troops, promising fair treatment and better lives to the Native Americans, Miles gradually persuaded the Indian nations to settle on the reservations. Not all the nations surrendered immediately, Miles went to battle against the holdouts with his troops, including during the extreme cold of winter. The Sioux and Crow bands migrated through wide areas in the Montana Territory, and troops were engaged in battle with them hundreds of miles from the fort. The fort was named for Myles Keogh, a Captain and commander of Company I in the 7th US Cavalry under Lt Colonel George Armstrong Custer, born in Ireland on March 25,1840, Keogh came from a comfortable background. Wanting adventure, Keogh left the farming to a brother and went off to war, in 1860 he went to Italy after the Pope recruited Irish men to take up the fight to save the Papal States. In those battles, he won two medals, later Keogh joined the Papal Guard in Rome
10.
Montana
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Montana /mɒnˈtænə/ is a state in the Western region of the United States. The states name is derived from the Spanish word montaña, Montana has several nicknames, although none official, including Big Sky Country and The Treasure State, and slogans that include Land of the Shining Mountains and more recently The Last Best Place. Montana has a 545-mile border with three Canadian provinces, British Columbia, Alberta, and Saskatchewan, the state to do so. It also borders North Dakota and South Dakota to the east, Wyoming to the south, Montana is ranked 4th in size, but 44th in population and 48th in population density of the 50 United States. The western third of Montana contains numerous mountain ranges, smaller island ranges are found throughout the state. In total,77 named ranges are part of the Rocky Mountains, the eastern half of Montana is characterized by western prairie terrain and badlands. The economy is based on agriculture, including ranching and cereal grain farming. Other significant economic activities include oil, gas, coal and hard rock mining, lumber, the health care, service, and government sectors also are significant to the states economy. Millions of tourists annually visit Glacier National Park, the Little Bighorn Battlefield National Monument, the name Montana comes from the Spanish word Montaña and the Latin word Montana, meaning mountain, or more broadly, mountainous country. Montaña del Norte was the name given by early Spanish explorers to the mountainous region of the west. The name was changed by Representatives Henry Wilson and Benjamin F. Harding, when Ashley presented a bill to establish a temporary government in 1864 for a new territory to be carved out of Idaho, he again chose Montana Territory. This time Rep. Samuel Cox, also of Ohio, objected to the name, Cox complained that the name was a misnomer given most of the territory was not mountainous and that a Native American name would be more appropriate than a Spanish one. Other names such as Shoshone were suggested, but it was decided that the Committee on Territories could name it whatever they wanted, with an area of 147,040 square miles, Montana is slightly larger than Japan. It is the fourth largest state in the United States after Alaska, Texas, and California, the largest landlocked U. S. state, and the worlds 56th largest national state/province subdivision. To the north, Montana shares a 545-mile border with three Canadian provinces, British Columbia, Alberta, and Saskatchewan, the state to do so. It borders North Dakota and South Dakota to the east, Wyoming to the south, the states topography is roughly defined by the Continental Divide, which splits much of the state into distinct eastern and western regions. Most of Montanas 100 or more named mountain ranges are in the western half. The Absaroka and Beartooth ranges in the states south-central part are part of the Central Rocky Mountains
11.
Dime (United States coin)
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The dime, in U. S. usage, is a ten-cent coin, one tenth of a United States dollar, labeled formally as one dime. The denomination was first authorized by the Coinage Act of 1792, the dime is the smallest in diameter and is the thinnest of all U. S. coins currently minted for circulation, being.705 inches in diameter and.053 inches in thickness. The obverse of the coin depicts the profile of President Franklin D. Roosevelt and the reverse boasts an olive branch, a torch, as of 2011, the dime coin cost 5.65 cents to produce. The word dime comes from the French word dîme, meaning tithe or tenth part, from the Latin decima. In the past prices have occasionally been quoted on signage and other materials in terms of dimes, abbreviated as d or a d with a slash through it as with the cent. The Coinage Act of 1792 established the dime, cent, and mill as subdivisions of the equal to 1⁄10. The first known proposal for a coinage system in the United States was made in 1783 by Thomas Jefferson, Benjamin Franklin, Alexander Hamilton. Hamilton, the nations first Secretary of the Treasury, recommended the issuance of six such coins in 1791, among the six was a silver coin, which shall be, in weight and value, one tenth part of a silver unit or dollar. Thus dimes are made small and thin, with the passage of the Coinage Act of 1965, the dimes silver content was removed. Dimes from 1965 to the present are composed of layers of 75 percent copper and 25 percent nickel. Starting in 1992, the U. S. Mint began issuing Silver Proof Sets annually and these sets are intended solely for collectors, and are not meant for general circulation. Since its introduction in 1796, the dime has been issued in six different major types, the name for each type indicates the design on the coins obverse. The composition of the disme was set at 89.24 percent silver and 10.76 percent copper, in 1792, a limited number of dismes were minted but never circulated. Some of these were struck in copper, indicating that the 1792 dismes were in fact pattern coins, the first dimes minted for circulation did not appear until 1796, due to a lack of demand for the coin and production problems at the United States Mint. The first dime to be circulated was the Draped Bust dime and it featured the same obverse and reverse as all other circulating coins of the time, the so-called Draped Bust/Small Eagle design. This design was the work of then-Chief Engraver Robert Scot, the portrait of Liberty on the obverse was based on a Gilbert Stuart drawing of prominent Philadelphia socialite Ann Willing Bingham, wife of noted American statesman William Bingham. The reverse design is of a bald eagle surrounded by palm and olive branches. Since the Coinage Act of 1792 required only that the cent and half cent display their denomination, all 1796 dimes have 15 stars on the obverse, representing the number of U. S. states then in the Union
12.
Graupel
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Graupel, also called soft hail or snow pellets, is precipitation that forms when supercooled droplets of water are collected and freeze on falling snowflakes, forming 2–5 mm balls of rime. The term graupel comes from the German language, the METAR code for graupel is GS. Under some atmospheric conditions, snow crystals may encounter supercooled water droplets and these droplets, which have a diameter of about 10 µm, can exist in the liquid state at temperatures as low as −40 °C, far below the normal freezing point. Contact between a crystal and the supercooled droplets results in freezing of the liquid droplets onto the surface of the crystal. This process of growth is known as accretion. Crystals that exhibit frozen droplets on their surfaces are referred to as rimed. When this process continues so that the shape of the snow crystal is no longer identifiable. Graupel was formerly referred to by meteorologists as soft hail, however, graupel is easily distinguishable from hail in both the shape and strength of the pellet and the circumstances in which it falls. Ice from hail is formed in hard, relatively uniform layers, graupel forms fragile, oblong shapes and falls in place of typical snowflakes in wintry mix situations, often in concert with ice pellets. Graupel is also fragile enough that it will fall apart when touched. However, observations of snow crystals with a scanning electron microscope clearly show cloud droplets measuring up to 50 µm on the surface of the crystals. The rime has been observed on all four forms of snow crystals, including plates, dendrites, columns. As the riming process continues, the mass of frozen, accumulated cloud droplets obscures the form of the snow crystal. Graupel commonly forms in high-altitude climates and is denser and more granular than ordinary snow, due to its rimed exterior. Macroscopically, graupel resembles small beads of polystyrene, the combination of density and low viscosity makes fresh layers of graupel unstable on slopes, and layers of 20–30 cm present a high risk of dangerous slab avalanches. In addition, thinner layers of graupel falling at low temperatures can act as ball bearings below subsequent falls of more stable snow. Graupel tends to compact and stabilise approximately one or two days after falling, depending on the temperature and the properties of the graupel, merriam-Webster Online Dictionary, accessed September 12,2006. The Weather Channel, accessed September 12,2006, national Snow and Ice Data Center, accessed September 12,2006
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