Norwegian train plowing through drifted snow Physical properties 0.1 – 0.8 g/cm 3 Mechanical properties (σ t) 1.5 – 3.5 kPa 3 – 7 MPa Thermal properties 0 °C For densities 0.1 to 0.5 g/cm 3 0.05 – 0.7 W K −1 m −1 Electrical properties For dry snow density 0.1 to 0.9 g/cm 3 1 – 3.2 The physical properties of snow vary considerably from event to event, sample to sample, and over time. Part of the series • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • () • • • () • () • • • • • • • • • • • • • • • • • •. • • • Snow refers to forms of crystals that precipitate from the atmosphere (usually from clouds) and undergo changes on the Earth's surface. It pertains to 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 away.

Organize and develop by feeding on sources of atmospheric moisture and cold air. Around particles in the atmosphere by attracting water droplets, which freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles, columns and. As snow accumulates into a, it may blow into drifts. Over time, accumulated snow metamorphoses, by, and.

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Where the climate is cold enough for year-to-year accumulation, a may form. Otherwise, snow typically melts seasonally, causing runoff into streams and rivers and recharging. Major snow-prone areas include the, the upper half of the and mountainous regions worldwide with sufficient moisture and cold temperatures. In the, snow is confined primarily to mountainous areas, apart from. Snow affects such human activities as: creating the need for keeping roadways, wings, and windows clear;: providing water to crops and safeguarding livestock; such as,, travel; and: impairing target acquisition, degrading the performance of combatants and materiel, and impeding mobility. Snow affects, as well, by providing an insulating layer during winter under which plants and animals are able to survive the cold. Any elevation: none.

Snow develops in clouds that themselves are part of 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. Cloud formation Snow clouds usually occur in 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.

Low pressure areas. Frontal snowsquall moving toward,. A, the leading edge of a cooler mass of air, can produce —an intense frontal line (similar to a ), when 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 but the motion of the line can cover large distances. Frontal squalls may form 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 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 only separated by 25 miles (40 kilometers) with each passing the same point in 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. A 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 the warm sector behind the front. Lake and ocean effects.

Cold northwesterly wind over and creating lake-effect snowfall. Lake-effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer water, warming the lower layer of air which picks up from the lake, rises up through the colder air above, freezes and is deposited on the (downwind) shores.

The same effect also occurs over bodies of salt water, when it is termed ocean-effect or bay-effect snow. The effect is enhanced when the moving air mass is uplifted by the influence of higher elevations on the downwind shores. This uplifting can produce narrow but very intense bands of precipitation, which 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.

These include areas east of the, the west coasts of northern Japan, the in Russia, and areas near the,,,, and parts of the northern Atlantic Ocean. Mountain effects. Main article: or relief snowfall is caused when masses of air pushed by are forced up the side of elevated land formations, such as large. The lifting of air up the side of a mountain or range results in cooling, and ultimately condensation and precipitation. Moisture is removed by orographic lift, leaving on the descending, leeward side.

The resulting enhanced productivity of snow fall and the with elevation means that snow depth and seasonal persistence of snowpack increases with elevation in snow-prone areas. Cloud physics. Freshly fallen snowflakes. A snowflake consists of roughly 10 19 water, 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 vary among themselves, while following similar patterns. Snow crystals form when tiny cloud droplets (about 10 in diameter). These droplets are able to remain liquid at temperatures lower than −18 °C (0 °F), because to freeze, a few molecules in the droplet need to get together by chance to form an arrangement similar to that in an ice lattice. Then 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 that cloud condensation nuclei on which liquid droplets form.

Clays, desert dust and biological particles can be nuclei. Artificial nuclei include particles of and, and these are used to stimulate precipitation in. Once 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 due to their sheer abundance, the crystals are able to grow to hundreds of or millimeters in size at the expense of the water droplets by the.

The corresponding depletion of water vapor causes the ice crystals to grow at the droplets' expense. 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 the crystal facets and hollows/imperfections mean that the crystals often appear white in color due to of the whole of by the small ice particles.

Classification of snowflakes. An early classification of snowflakes. Of thousands of snowflakes from 1885 onward, starting with, revealed the wide diversity of snowflakes within a classifiable set of patterns. Closely matching snow crystals have been observed. Nakaya developed a crystal morphology diagram, relating crystal shapes to the temperature and moisture conditions under which they formed, which is summarized in the following table. An animation of seasonal snow changes, based on satellite imagery. Snow accumulates from 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 or with a standard, adjusted for winter by removal of a funnel and inner cylinder. Both types of gauges melt the accumulated snow and report the amount of water collected.

At some an ultrasonic snow depth sensor may be used to augment the precipitation gauge. Snow events, and describe snow events of progressively greater duration and intensity. A is a weather condition involving snow and has varying definitions in different parts of the world. In the, 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 (56 km/h), and sufficient snow in the air to reduce visibility to less than 0.4 kilometers (0.25 mi). In and the, the criteria are similar. While heavy snowfall often occurs during blizzard conditions, falling snow is not a requirement, as can create a.

Snowstorm intensity may be categorized by visibility and depth of accumulation. Snowfall's intensity is determined by, as follows: • Light: visibility greater than 1 kilometer (0.6 mi) • Moderate: visibility restrictions between 0.5 and 1 kilometer (0.3 and 0.6 mi) • Heavy: visibility is less than 0.5 kilometers (0.3 mi) The International Classification for Seasonal Snow on 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 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 the difficulty of measuring snowfall.

Distribution 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 ^ 6 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 a minimum extent of 2 million square kilometres (0.77 × 10 ^ 6 sq mi) each August to a maximum extent of 45 million square kilometres (17 × 10 ^ 6 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 ^ 6 sq mi) over the 35-year period. Records The following are world records, regarding snowfall and snowflakes: • Highest seasonal total snowfall – The world record for the highest seasonal total snowfall was measured in the at, outside of the town, during the 1998–1999 season.

Mount Baker received 2,896 cm (95.01 ft) of snow, thus surpassing the previous record holder,, Washington, which during the 1971–1972 season received 2,850 cm (93.5 ft) of snow. • Highest seasonal average annual snowfall – The world record for the highest average annual snowfall is 1,764 cm (57.87 ft), measured in, Japan for the period of 1981–2010.

• Largest snowflakes – Guinness World Records list the world's largest snowflakes as those of January 1887 at Fort Keogh, Montana; allegedly one measured 38 cm (15 in) wide. Fresh snow beginning to metamorphose: The surface shows wind packing and. In the foreground are crystals, formed by refrozen water vapor emerging to the cold surface. After deposition, snow progresses on one of two paths that determine its fate, either ablation (mostly by melting) or transitioning from (multi-year snow) into glacier ice.

During this transition, snow 'is 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 in a process, known as metamorphism, wherein all three phases of water may coexist, including liquid water partially filling the pore space. 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. Kamidori Alchemy Meister Full Save File here. Water vapor plays a role as it deposits ice crystals, known as, during cold, still conditions. Seasonal snowpack. —metamorphosed multi-year snow. Firn is snow that has persisted for multiple years and has been into a substance denser than, yet less dense and hard than glacial.

Firn resembles caked sugar and is very resistant to shovelling. Its density generally ranges from 550 kilograms per cubic metre (34 lb/cu ft) to 830 kilograms per cubic metre (52 lb/cu ft), and it can often be found underneath the snow that accumulates at the head of a.

The minimum altitude that firn accumulates on a glacier is called the firn limit, firn line or snowline. Movement 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 the movement of glaciers after snow has persisted for multiple years and metamorphosed into glacier ice. A powder snow avalanche.

An avalanche (also called 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 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.

They occur in three major mechanisms: • Slab avalanches occur in snow that has been deposited, or redeposited by wind. They have the characteristic appearance of a block (slab) of snow cut out from its surroundings by fractures. These account for most back-country fatalities. • result from a deposition of fresh dry powder and generate a powder cloud, which overlies a dense avalanche. They can exceed speeds of 300 kilometres per hour (190 mph), and masses of 10,000,000 tonnes (9,800,000 long tons; 11,000,000 short tons); their flows can travel long distances along flat valley bottoms and even uphill for short distances. • Wet snow avalanches are a low-velocity suspension of snow and water, with the flow confined to the surface of the pathway. The low speed of travel is due to the friction between the sliding surface of the pathway and the water saturated flow.

Despite the low speed of travel (~10 to 40 kilometres per hour (6 to 25 mph)), wet snow avalanches are capable of generating powerful destructive forces, due to the large mass, and density. Snowmelt-induced flooding of the in.

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 during the spring months and at least in dry mountainous regions like the mountain West of the US or most of and, very low flow for the rest of the year. In contrast, if much of the melt is from or nearly glaciated areas, the melt continues through the warm season, with peak flows occurring in mid to late summer. Main article: Scientists study snow at a wide variety of scales that include the of and; the distribution, accumulation, metamorphosis, and ablation of snowpacks; and the contribution of snowmelt to river and ground. In doing so, they employ a variety of instruments to observe and measure the phenomena studied.

Their findings contribute to knowledge applied by, who adapt vehicles and structures to snow, by, who address the availability of snowmelt to, 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 the individual crystal to the aggregated snowpack. A sub-specialty is, 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 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 and techniques to develop understanding of snow-related processes over large areas. Measurement and classification. Snow pit on the surface of a glacier, profiling snow properties where the snow becomes increasingly dense with depth as it metamorphoses towards ice. 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 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. Snowfall and snowmelt are parts of the Earth's water cycle. Snow science often leads to predictive models that include snow deposition, snow melt, and snow hydrology—elements of the Earth's —which help describe. (GCMs) incorporate snow as a factor in their calculations. Some important aspects of snow cover include its (reflectivity of incident radiation, including light) and insulating qualities, which slow the rate of seasonal melting of sea ice.

As of 2011, the melt phase of GCM snow models were thought to perform poorly in regions with complex factors that regulate snow melt, such as vegetation cover and terrain. These models typically derive snow water equivalent (SWE) in some manner from satellite observations of snow cover. The International Classification for Seasonal Snow on the Ground defines SWE as 'the depth of water that would result if the mass of snow melted completely'. Given the importance of snowmelt to agriculture, hydrological runoff models that include snow in their predictions address the phases of accumulating snowpack, melting processes, and distribution of the meltwater through stream networks and into the groundwater. Key to describing the melting processes are solar heat flux, ambient temperature, wind, and precipitation.

Initial snowmelt models used a degree-day approach that emphasized the temperature difference between the air and the snowpack to compute snow water equivalent, SWE. More recent models use an energy balance approach that take into account the following factors to compute Q m, the energy available for melt. This requires measurement of an array of snowpack and environmental factors to compute six heat flow mechanisms that contribute to Q m. Effects on human activity Snow affects human activity in four major areas, transportation, agriculture, structures, and sports.

Most transportation modes are impeded by snow on the travel surface. Agriculture often relies on snow as a source of seasonal moisture.

Structures may fail under snow loads. Humans find a wide variety of recreational activities in snowy landscapes. Traffic stranded in a 2011 snowstorm. In the late 20th Century, an estimated $2 billion was spent annually in North America on roadway winter maintenance, owing to snow and other winter weather events, according to a 1994 report by Kuemmel. The study surveyed the practices of jurisdictions within 44 US states and nine Canadian provinces. It assessed the policies, practices, and equipment used for winter maintenance.

It found similar practices and progress to be prevalent in Europe. The dominant effect of snow on vehicle contact with the road is diminished friction. This can be improved with the use of, which have a tread designed to compact snow in a manner that enhances traction. However, the key to maintaining a roadway that can accommodate traffic during and after a snow event is an effective anti-icing program that employs both chemicals and.

The Manual of Practice for an Effective Anti-icing Program emphasizes 'anti-icing' procedures that prevent the bonding of snow and ice to the road. Key aspects of the practice include: understanding anti-icing in light of the level of service to be achieved on a given roadway, the climatic conditions to be encountered, and the different roles of deicing, anti-icing, and abrasive materials and applications, and employing anti-icing 'toolboxes', one for operations, one for decision-making and another for personnel.

The elements to the toolboxes are: • Operations – Addresses the application of solid and liquid chemicals, using various techniques, including prewetting of chloride-salts. It also addresses plowing capability, including types of snowplows and blades used. Torrent Html5 Builder Software.

• Decision-making – Combines weather forecast information with road information to assess the upcoming needs for application of assets and the evaluation of treatment effectiveness with operations underway. • Personnel – Addresses training and deployment of staff to effectively execute the anti-icing program, using the appropriate materials, equipment and procedures. The manual offers matrices that address different types of snow and the rate of snowfall to tailor applications appropriately and efficiently., constructed upwind of roadways control snow drifting by causing windblown, drifting snow to accumulate in a desired place.

They are also used on railways. Additionally, farmers and ranchers use snow fences to create drifts in basins for a ready supply of water in the spring. Deicing an aircraft during a snow event. In order to keep airports open during winter storms, runways and taxiways require snow removal.

Unlike roadways, where chloride chemical treatment is common to prevent snow from bonding to the pavement surface, such chemicals are typically banned from airports because of their strong corrosive effect on aluminum aircraft. Consequently, mechanical brushes are often used to complement the action of snow plows. Given the width of runways on airfields that handle large aircraft, vehicles with large plow blades, an echelon of plow vehicles or are used to clear snow on runways and taxiways. Terminal aprons may require 6 hectares (15 acres) or more to be cleared. Properly equipped aircraft are able to fly through snowstorms under. Prior to takeoff, during snowstorms they require to prevent accumulation and freezing of snow and other precipitation on wings and fuselages, which may compromise the safety of the aircraft and its occupants. In flight, aircraft rely on a variety of mechanisms to avoid rime and other types of icing in clouds, these include pulsing, electro-thermal areas that generate heat, and fluid deicers that bleed onto the surface.

Rail Railroads have traditionally employed two types of snow plows for clearing track, the, which casts snow to both sides, and the rotary snowplow, which is suited for addressing heavy snowfall and casting snow far to one side or the other. Prior to the invention of the rotary snowplow ca. 1865, it required multiple to drive a wedge plow through deep snow. Subsequent to clearing the track with such plows, a 'flanger' is used to clear snow from between the rails that are below the reach of the other types of plow. Where icing may affect the steel-to-steel contact of locomotive wheels on track, abrasives (typically sand) have been used to provide traction on steeper uphills.

Railroads employ —structures that cover the track—to prevent the accumulation of heavy snow or avalanches to cover tracks in snowy mountainous areas, such as the and the. Snowplows for different transportation modes •. Satellite view of the Indus River, showing snow in the Himalayas, which feeds it, and green areas that draw on it for irrigation. Snowfall can be beneficial to agriculture by serving as a, conserving the heat of the Earth and protecting from subfreezing weather. Some agricultural areas depend on an accumulation of snow during winter that will melt gradually in spring, providing water for crop growth, both directly and via runoff through streams and rivers, which supply irrigation canals.

The following are examples of rivers that rely on meltwater from glaciers or seasonal snowpack as an important part of their flow on which irrigation depends: the, many of whose tributaries rise in the and which provide much irrigation in northeast, the, which rises in and provides irrigation water to from rapidly retreating Tibetan glaciers, and the, which receives much of its water from seasonal snowpack in the and provides irrigation water to some 4 million acres (1.6 million hectares). Icings resulting from water leaking through the roof due to an ice dam, caused by snowmelt on the roof.

Snow loads and icings are two principal issues for roofs. Snow loads are related to the climate in which a structure is sited. Icings are usually a result of the building or structure generating heat that melts the snow that is on it. Snow loads – The Minimum Design Loads for Buildings and Other Structures gives guidance on how to translate the following factors into roof snow loads: • Ground snow loads • Exposure of the roof • Thermal properties of the roof • Shape of the roof • Drifting • Importance of the building It gives tables for ground snow loads by region and a methodology for computing ground snow loads that may vary with elevation from nearby, measured values. The Eurocode 1 uses similar methodologies, starting with ground snow loads that are tabulated for portions of Europe. Icings – Roofs must also be designed to avoid, which result from meltwater running under the snow on the roof and freezing at the eave. Ice dams on roofs form when accumulated snow on a sloping roof melts and flows down the roof, under the insulating blanket of snow, until it reaches below freezing temperature air, typically at the.

When the meltwater reaches the freezing air, ice accumulates, forming a dam, and snow that melts later cannot drain properly through the dam. Ice dams may result in building materials or in damage or injury when the ice dam falls off or from attempts to remove ice dams.

The melting results from heat passing through the roof under the highly insulating layer of snow. Utility lines In areas with trees, utility distribution lines on poles are less susceptible to snow loads than they are subject to damage from trees falling on them, felled by heavy, wet snow. Elsewhere, snow can accrete on power lines as 'sleeves' of rime ice. Engineers design for such loads, which are measured in kg/m (lb/ft) and power companies have forecasting systems that anticipate types of weather that may cause such accretions. Rime ice may be removed manually or by creating a sufficient short circuit in the affected segment of power lines to melt the accretions. Sports and recreation.

Main article: Snow figures into many winter sports and forms of recreation, including and. Common examples include,,,, and. The design of the equipment used, typically relies on the bearing strength of snow, as with skis or snowboards and contends with the of snow to allow sliding, often enhance.

By far the largest form of winter recreation is skiing. As of 1994, of the estimated 65–75 million skiers worldwide, there were approximately 55 million who engaged in, the rest engaged in. Approximately 30 million skiers (of all kinds) were in Europe, 15 million in the US, and 14 million in Japan. As of 1996, there were reportedly 4,500 ski areas, operating 26,000 ski lifts and enjoying 390 million skier visits per year. The preponderant region for downhill skiing was Europe, followed by Japan and the US. Increasingly, ski resorts are relying on, the production of snow by forcing water and pressurized air through a on ski slopes.

Snowmaking is mainly used to supplement natural snow. This allows them to improve the reliability of their snow cover and to extend their ski seasons from late autumn to early spring. The production of snow requires low temperatures. The threshold temperature for snowmaking increases as humidity decreases. Is used as a metric since it takes air temperature and relative humidity into account. Snowmaking is a relatively expensive process in its energy consumption, thereby limiting its use. Enhances the ability of a ski or other runner to slide over snow, which depends on both the properties of the snow and the ski to result in an optimum amount of lubrication from melting the snow by friction with the ski—too little and the ski interacts with solid snow crystals, too much and capillary attraction of meltwater retards the ski.

Before a ski can slide, it must overcome the maximum value static friction. Kinetic (or dynamic) friction occurs when the ski is moving over the snow.

See also: Snow affects warfare conducted in winter, alpine environments or at high latitudes. The main factors are impaired visibility for acquiring targets during falling snow, enhanced visibility of targets against snowy backgrounds for targeting, and mobility for both and troops. Snowfall can severely inhibit the, as well. Snow can also provide cover and fortification against small-arms fire.

Noted campaigns where snow and other factors affected the operations include: • The, where poor traction conditions for ill-shod horses made it difficult for supply wagons to keep up with troops. That campaign was also strongly affected by cold, whereby the retreating army reached in December 1812 with only 10,000 of the 420,000 that had set out to invade in June of the same year. • The, an attempt by the to take territory in in late 1939 demonstrated superior winter tactics of the, regarding over-snow mobility,, and use of the terrain. • The, a German counteroffensive during, starting December 16, 1944, was marked by heavy snowstorms that hampered allied air support for ground troops, but also impaired German attempts to supply their front lines.

On the Eastern Front with the Nazi invasion of Russia in 1941,, both Russian and German soldiers had to endure terrible conditions during the. While use of was common in the Red Army, Germany formed only for movement on skis. • The which lasted from June 25, 1950, until an armistice in July 27, 1953, began when invaded. Much of the fighting occurred during winter conditions, involving snow, notably during the, which was a stark example of cold affecting military operations, especially vehicles and weapons. Military operations in snow •.

Algae,, that thrive in snow form red areas in the on this snow surface. Both plant and animal life endemic to snow-bound areas develop ways to adapt. Among the adaptive mechanisms for plants are dormancy, seasonal dieback, survival of seeds; and for animals are hibernation, insulation, anti-freeze chemistry, storing food, drawing on reserves from within the body, and clustering for mutual heat.

Plant life Snow interacts with vegetation in two principal ways, vegetation can influence the deposition and retention of snow and, conversely, the presence of snow can affect the distribution and growth of vegetation. Tree branches, especially of intercept falling snow and prevent accumulation on the ground. Snow suspended in trees ablates more rapidly than that on the ground, owing to its greater exposure to sun and air movement.

Trees and other plants can also promote snow retention on the ground, which would otherwise be blown elsewhere or melted by the sun. Snow affects vegetation in several ways, the presence of stored water can promote growth, yet the annual onset of growth is dependent on the departure of the snowpack for those plants that are buried beneath it.

Furthermore, avalanches and erosion from snowmelt can scour terrain of vegetation. A predator of smaller animals that live beneath the snow Snow supports a wide variety of animals both on the surface and beneath.

Many thrive in snow, including,,, and. Such are typically active at temperatures down to −5 °C (23 °F). Invertebrates fall into two groups, regarding surviving subfreezing temperatures: freezing resistant and those that avoid freezing because they are freeze-sensitive. The first group may be cold hardy owing to the ability to produce agents in their body fluids that allows survival of long exposure to sub-freezing conditions. Some organisms during the winter, which expels freezing-sensitive contents from their digestive tracts.

The ability to survive the absence of oxygen in ice is an additional survival mechanism. Small are active beneath the snow. Among vertebrates, are active in snow at temperatures as low as −8 °C (18 °F); they burrow to the surface in springtime and lay their eggs in melt ponds.

Among mammals, those that remain active are typically smaller than 250 grams (8.8 oz). Are more likely to enter a torpor or be, whereas are more likely to maintain food caches beneath the snow. Store up to 3 kilograms (6.6 lb) of food and up to 20 kilograms (44 lb).

Voles also huddle in communal nests to benefit from one another's warmth. On the surface,,,,, and rely on these subsurface dwellers for food and often dive into the snowpack to find them.

Extraterrestrial snow Extraterrestrial 'snow' includes water-based precipitation, but also precipitation of other compounds prevalent on other planets and moons in the. Examples are: • On, observations of the reveal that water-based snow crystals occur at high latitudes. Additionally, precipitates from clouds during the Martian winters at the poles and contributes to a seasonal deposit of that compound, which is the principal component of that. • On, observations from the reveal the presence a metallic substance, which precipitates as ' and leaves a highly reflective substance at the tops of Venus's highest mountain peaks resembling terrestrial snow. Given the high temperatures on Venus, the leading candidates for the precipitate are and. • On 's moon,, observations suggest the presence of or some other form of -based crystalline deposits.

By on January 30, 2014 in British historical novelist Richard Denning explains the very popular Snowflake Method for planning and writing novels, illustrated by examples from one of his seven YA (young adult) novels, The Last Seal. As a a self-published author of historical fiction and historical fantasy, I use the Snowflake Method to help me write novels. It was invented by, the multiple-award-winning US novelist and teacher of writing crafts. Why Use the Snowflake Method? The idea of the Snowflake Method is that, if it is done well, you can avoid major plot issues requiring major rewrites because you already have done that work. Furthermore you should spend less time staring at a blank page.

You wrench the story idea out of your head at the start. Once you have built the snowflake it makes the writing easier. This does not mean you lose creativity. You have to be creative at the start as you make the snowflake.

As you go along you often find new ideas pop up – indeed these can often be stimulated more because you already know the direction the novel is going and so your flakes of inspiration can link in better. How To Use The Snowflake Method I summarise the main steps here, using my YA historical novel The Last Seal as an example: STEP 1 ONE SENTENCE SUMMARY Write a one-sentence summary of your novel. This sentence could become the hook that will sell your book. A good sentence is shorter rather than longer – ideally fewer than 15 words.

It should not contain character names. It is better to say “a mercenary time travelling adventurer” than “Septimus Mason”. This sentence should aim to tie together the big picture of the book with the personal picture of the main character. We should learn which character has the most to lose in this story and what he or she wants to gain. Here’s a one sentence summary of my YA novel, The Last Seal: “London 1666: a schoolboy and a thief brave the perils of the Great Fire to prevent an even more terrible catastrophe!” STEP 2 ONE PARAGRAPH PLOT You now need to expand that sentence to a full paragraph describing the background, the major disasters, and the ending of the novel.

It is a good idea to think about the a story as “three disasters plus an ending”. Each of the disasters takes a quarter of the book to develop and the ending takes the final quarter. If you are approaching publishers you can also use this paragraph in your proposal. Or alternatively if you self-publish this could easily become the back cover blurb. Ideally, your paragraph will have about five sentences: one sentence to give me the backdrop and story setup, one sentence each for your three disasters, then one more sentence to tell the ending.

Here’s my one-paragraph plot for The Last Seal: “In September 1666 a schoolboy playing truant and a local thief blunder into a struggle between rival secret societies. They discover that the Liberati serve a powerful demon which was locked under London by their opponents the Praesidum who created magical seals round the city which now the Liberati aim to destroy when they start the fire at Pudding Lane. As the fire spreads, the two youths and the Praesidum must evade the deadly Liberati as they try to locate the remaining seals.

They discover that the location of the final seal is given on a secret key hidden somewhere in the city. A desperate race ensues to find the key, locate the final seal and prevent the demon being freed.” STEP 3 DEVELOP CHARACTERS Plots are all very good but the book is going to need compelling characters. So you need something similar for the storylines of each of your characters. For each of your major characters, we need this information: • The character’s name • A one-sentence summary of the character’s storyline • The character’s goal (what does he/she want?) • The character’s conflict (what prevents him/her from reaching this goal?) • The character’s epiphany (what will he/she learn, how will he/she change? A one-paragraph summary of the character’s storyline I developed this profile for my character Freya in The Last Seal: • Summary: Cheerful, cheeky but, selfish young thief finds a purpose through perilous adventure. • Goal: To survive each day and get as much as she can.

To gain wealth, avoid responsibility • Obstacles: Uneducated, orphan gutter snipe with no prospects • Epiphany: There are things more important than self, higher purposes which are worth risking self for • Synopsis of character story line: Freya scrapes a living thieving and pick-pocketing. One day she is caught red handed and shifts the blame on Benjamin a school boy playing truant who runs with her to escape capture right into an encounter with agents of the Liberati who threaten them both.

Escaping with Ben they encountering the Praesidum. Initially she refuses to help the Praesidum unless she gains a reward but gradually comes to realise that the Liberati must be opposed and in so doing her shallow existence gains meaning.

Helps reforms the Praesidum at the end and resolves to continue its mission. STEP 4 PLOT SUMMARY The snow flake grows.

You now expand the one paragraph summary of the plot. Each sentence expands into a full paragraph. All but the last paragraph should end in a disaster. The final paragraph should tell how the book ends. So you now have maybe a full sheet with your plot on. STEP 5 CHARACTER CHARTS Take your character synopsis and now expand your character descriptions into full-fledged character charts. Detail everything there is to know about each character, such as birthdate, description, history, motivation, goals, etc. STEP 6 EXPAND THE PLOT SYNOPSIS By now, you have a solid story and several story-threads, one for each character.

Now expand the one-page plot synopsis of the novel to a four-page synopsis. Basically, you will again be expanding each paragraph from step (4) into a full page. Take that four-page synopsis and make a list of all the scenes that you’ll need to turn the story into a novel. Make a list of each scene throughout the whole books and organise them into chapters. Here’s how I did it for The Last Seal: At this point I open up Word and slap in all those scenes. Then I just sit down and start pounding out the real first draft of the novel.

If I follow this process well (and I confess I don’t always manage to be quite so elaborate), I am often astounded at how fast the story flies out of my fingers at this stage. • I KNOW the story • I KNOW the characters • I KNOW the scenes • I can just get writing! Seat of pants writers may not like this approach but I find I need the framework to get me started. Randy Ingermanson offers more information about his Snowflake Method and much more writing advice at his excellent website,. I bought the Snowflake program on my old PC and used it to make a storyline. I never wrote that story as planned, but Snowflake certainly helped me to make the plot and characters clear in my head. Still, the story doesn’t end there – I bought a Mac, but did not buy the Mac version of the Snowflake (yet).

The story line I created with Snowflake for was used as basis of the novel I have now written – I just took another angle to the story. My writing style is such that the characters seem to surprise me by doing unplanned things and the story goes to quite another direction than my original intention was, but I think the Snowflake is still good to use. You can tweak your story line later, if necessary, or create a completely new one. For writers whose writing seems to be all over the place, the method can give a nice framework and maybe some discipline to write.

Hi Richard: Glad to see you like my Snowflake method! When I first posted the Snowflake article on my web site, I had no idea it would become so popular all around the world. I thought a few people might find it interesting.

In my opinion, there is no one best way to get your first draft written. The Snowflake method is one “creative paradigm” but there are plenty of others, such as the Seat of the Pants method, the Edit As You Go method, and the outliner method.

Whatever works for you is what works for you. The value of talking about creative paradigms is that when you see how other writers do it, you sometimes realize that you have other options. People email me all the time to say that the Snowflake has liberated them–they thought a writer was supposed to just write to a blank page with no preparation. Of course, other writers would feel like the Snowflake is a pair of handcuffs on their creativity–they really need that blank page. To each his own. I was interested in the article as I’d seen this idea elsewhere I use a similar method and find it really suits me though as you say, there are other ways. Where I found it was in a women’s writing mag, and to kick off you write a 50-word sentence, I think, then you do a synopsis in 10 50-word points, expand to 500-words etc all based on the expanding synopsis similar but not the same.

What is so good about these methods is that the whole is made up of parts, so the parts (if you want to) can continue to be worked on as sections/parts and the whole doesn’t look such an enormous enterprise! Thanks for article. I’ve used this – but I didn’t know it by any name at all keeping head well down, I suspect I half thought it up myself and half adapted it from a book on writingor from something in Mslexia magazine. It can work well: though not so easy when you are doing a follow-up (as I am) and have your characters already there – only their younger selves. On the up side, I had a good idea what was going to happen event-wise. On the down side, it’s still involved re-writes (am doing those now) as turned out not tight enough – BUT that may’ve been because I did allow/find necessary a few areas needed expanding to clarify plot.

Anyhow, many thanks for posting: shall try to use the method again, with more precision next time!