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, which freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles, columns and rime. As snow accumulates into a snowpack, it may blow into drifts. Over time, accumulated snow metamorphoses, by sintering, sublimation and freeze-thaw. Where the climate is cold enough for year-to-year accumulation, a glacier may form. Otherwise, snow typically melts seasonally, causing runoff into streams and rivers and recharging groundwater.

Major snow-prone areas include the polar regions, the northernmost half of the Northern Hemisphere and mountainous regions worldwide with sufficient moisture and cold temperatures. In the Southern Hemisphere, snow is confined primarily to mountainous areas, apart from Antarctica.[3]

Snow Gta Free Download

tag_hash_104 🔥 https://cinurl.com/2yjWxm 🔥

Snow affects such human activities as transportation: creating the need for keeping roadways, wings, and windows clear; agriculture: providing water to crops and safeguarding livestock; sports such as skiing, snowboarding, and snowmachine travel; and warfare. Snow affects ecosystems, as well, by providing an insulating layer during winter under which plants and animals are able to survive the cold.[1]

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.[4]

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.

Mid-latitude cyclones are low-pressure areas which are capable of producing anything from cloudiness and mild snow storms to heavy blizzards.[5] During a hemisphere's fall, winter, and spring, the atmosphere over continents can be cold enough through the depth of the troposphere to cause snowfall. In the Northern Hemisphere, the northern side of the low-pressure area produces the most snow.[6] For the southern mid-latitudes, the side of a cyclone that produces the most snow is the southern side.

A warm front can produce snow for a period as warm, moist air overrides below-freezing air and creates precipitation at the boundary. Often, snow transitions to rain in the warm sector behind the front.[7]

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.[8][9]

The same effect occurring over bodies of salt water is termed ocean-effect or bay-effect snow. The effect is enhanced when the moving air mass is uplifted by the orographic influence of higher elevations on the downwind shores. This uplifting can produce narrow but very intense bands of precipitation which may deposit at a rate of many inches of snow each hour, often resulting in a large amount of total snowfall.[10]

The areas affected by lake-effect snow are called snowbelts. These include areas east of the Great Lakes, the west coasts of northern Japan, the Kamchatka Peninsula in Russia, and areas near the Great Salt Lake, Black Sea, Caspian Sea, Baltic Sea, and parts of the northern Atlantic Ocean.[11]

Orographic or relief snowfall is created when moist air is forced up the windward side of mountain ranges by a large-scale wind flow. The lifting of moist air up the side of a mountain range results in adiabatic cooling, and ultimately condensation and precipitation. Moisture is gradually removed from the air by this process, leaving drier and warmer air on the descending, or leeward, side.[12] The resulting enhanced snowfall,[13] along with the decrease in temperature with elevation,[14] combine to increase snow depth and seasonal persistence of snowpack in snow-prone areas.[1][15]

A snowflake consists of roughly 1019 water molecules which are added to its core at different rates and in different patterns depending on the changing temperature and humidity within the atmosphere that the snowflake falls through on its way to the ground. As a result, snowflakes differ from each other though they follow similar patterns.[17][18][19]

Micrography of thousands of snowflakes from 1885 onward, starting with Wilson Alwyn Bentley, revealed the wide diversity of snowflakes within a classifiable set of patterns.[25] Closely matching snow crystals have been observed.[26]

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 snow gauge[31] or with a standard rain gauge, adjusted for winter by removal of a funnel and inner cylinder.[32] Both types of gauges melt the accumulated snow and report the amount of water collected.[33] At some automatic weather stations an ultrasonic snow depth sensor may be used to augment the precipitation gauge.[34]

Snow flurry, snow shower, snow storm and blizzard describe snow events of progressively greater duration and intensity.[35] A blizzard is a weather condition involving snow and has varying definitions in different parts of the world. In the United States, a blizzard occurs when two conditions are met for a period of three hours or more: a sustained wind or frequent gusts to 35 miles per hour (16 m/s), and sufficient snow in the air to reduce visibility to less than 0.4 kilometers (0.25 mi).[36] In Canada and the United Kingdom, the criteria are similar.[37][38] While heavy snowfall often occurs during blizzard conditions, falling snow is not a requirement, as blowing snow can create a ground blizzard.[39]

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 snowboard during an observation period of 24 hours, or other observation interval. After the measurement, the snow is cleared from the board and the board is placed flush with the snow surface to provide an accurate measurement at the end of the next interval.[4] Melting, compacting, blowing and drifting contribute to the difficulty of measuring snowfall.[45]

The cities (more than 100,000 inhabitants) with the highest annual snowfall are Aomori (792 cm), Sapporo (485 cm) and Toyama (363 cm) in Japan, followed by St. John's (332 cm) and Quebec City (315 cm) in Canada, and Syracuse, NY (325cm).[53]

According to the International Association of Cryospheric Sciences, snow metamorphism is "the transformation that the snow undergoes in the period from deposition to either melting or passage to glacial ice".[4] Starting as a powdery deposition, snow becomes more granular when it begins to compact under its own weight, be blown by the wind, sinter particles together and commence the cycle of melting and refreezing. Water vapor plays a role as it deposits ice crystals, known as hoar frost, during cold, still conditions.[54] 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 wherein all three phases of water may coexist, including liquid water partially filling the pore space. After deposition, snow progresses on one of two paths that determine its fate, either by ablation (mostly by melting) from a snow fall or seasonal snowpack, or by transitioning from firn (multi-year snow) into glacier ice.[4]

Over the course of time, a snowpack may settle under its own weight until its density is approximately 30% of water. Increases in density above this initial compression occur primarily by melting and refreezing, caused by temperatures above freezing or by direct solar radiation. In colder climates, snow lies on the ground all winter. By late spring, snow densities typically reach a maximum of 50% of water.[55] Snow that persists into summer evolves into nv, granular snow, which has been partially melted, refrozen and compacted. Nv has a minimum density of 500 kilograms per cubic metre (31 lb/cu ft), which is roughly half of the density of liquid water.[56]

Firn is snow that has persisted for multiple years and has been recrystallized into a substance denser than nv, yet less dense and hard than glacial ice. 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 glacier. The minimum altitude that firn accumulates on a glacier is called the firn limit, firn line or snowline.[1][57]

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.

When powdery snow drifts with the wind from the location where it originally fell,[58] forming deposits with a depth of several meters in isolated locations.[59] After attaching to hillsides, blown snow can evolve into a snow slab, which is an avalanche hazard on steep slopes.[60] 0852c4b9a8

free download of 50 shades darker pdf

rpc plugin for max 9 free download

free big sean guap mp3 download