Norwegian train plowing through drifted snow
Extratropical cyclonic snowstorm, February 24, 2007—(Click for animation.)
Frontal snowsquall moving toward Boston, Massachusetts
Cold northwesterly wind over Lake Superior and Lake Michigan creating lake-effect snowfall
Freshly fallen snowflakes
An early classification of snowflakes by Israel Perkins Warren
An animation of seasonal snow changes, based on satellite imagery
New York City during a 2016 blizzard, which
 produced local wind gusts up to 42 mph and dropped 27.5 in of snow, breaking the city's one-day snowfall record.
Snow-covered trees in Kuusamo, Finland
Fresh snow beginning to metamorphose: The surface shows wind packing and sastrugi. In the foreground are hoar frost crystals, formed by refrozen water vapor emerging to the cold surface.
Firn—metamorphosed multi-year snow
Snow drifts forming around downwind obstructions
A powder snow avalanche
Snowmelt-induced flooding of the Red River of the North in 1997
Snow pit on the surface of a glacier, profiling snow properties where the snow becomes increasingly dense with depth as it metamorphoses towards ice
Snowfall and snowmelt are parts of the Earth's water cycle.
Traffic stranded in a 2011 Chicago snowstorm.
Winter conditions on Ontario Highway 401 in Toronto due to a snowsquall.
Deicing an aircraft during a snow event
Satellite view of the Indus River, showing snow in the Himalayas, which feeds it, and agricultural areas in Pakistan that draw on it for irrigation.
Extreme snow accumulation on building roofs
Icings resulting from meltwater at the bottom of the snow pack on the roof, flowing and refreezing at the eave as icicles and from leaking into the wall via an ice dam.
Alpine skiing.
Algae, Chlamydomonas nivalis, that thrive in snow form red areas in the suncups on this snow surface
Arctic fox, a predator of smaller animals that live beneath the snow
Trucks plowing snow on a highway in Missouri
Airport snow-clearing operations include plowing and brushing
Swiss low-profile, train-mounted snowplow
Bivouac of Napoleon's Grande Armée, during the winter retreat from Moscow
Finnish ski troops during the invasion of Finland by the Soviet Union
Army vehicles coping with snow during the Battle of the Bulge of World War II.
Norwegian military preparations during the 2009 Cold Response exercise
Navy SEALs training for winter warfare at Mammoth Mountain, California.

Snow comprises individual ice crystals that grow while suspended in the atmosphere—usually within clouds—and then fall, accumulating on the ground where they undergo further changes.

- Snow

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Lake-effect snow is the cause of the regional nickname

The Snowbelt is the region near the Great Lakes in North America where heavy snowfall in the form of lake-effect snow is particularly common.


A powder snow avalanche in the Himalayas near Mount Everest.
Heavy equipment in action after an avalanche has interrupted service on the Saint-Gervais–Vallorcine railway in Haute-Savoie, France (2006).
The terminus of an avalanche in Alaska's Kenai Fjords.
Loose snow avalanches (far left) and slab avalanches (near center) near Mount Shuksan in the North Cascades mountains. Fracture propagation is relatively limited.
15 cm deep, soft slab avalanche triggered by a snowboarder near Heliotrope Ridge, Mount Baker in March 2010. Multiple crown fracture lines are visible in the top-middle of the image. Note the granular characteristic of the debris in the foreground that results from the slab breaking up during descent.
Avalanche on Simplon Pass (2019)
In steep avalanche-prone terrain, traveling on ridges is generally safer than traversing the slopes.
A cornice of snow about to fall. Cracks in the snow are visible in area (1). Area (3) fell soon after this picture was taken, leaving area (2) as the new edge.
Avalanche path with 800 m vertical fall in the Glacier Peak Wilderness, Washington state. Avalanche paths in alpine terrain may be poorly defined because of limited vegetation. Below tree line, avalanche paths are often delineated by vegetative trim lines created by past avalanches. The start zone is visible near the top of the image, the track is in the middle of the image and clearly denoted by vegetative trimlines, and the runout zone is shown at the bottom of the image. One possible timeline is as follows: an avalanche forms in the start zone near the ridge, and then descends the track, until coming to rest in the runout zone.
After surface hoarfrost becomes buried by later snowfall, the buried hoar layer can be a weak layer upon which upper layers can slide.
After digging a snow pit, it is possible to evaluate the snowpack for unstable layers. In this picture, snow from a weak layer has been easily scraped away by hand, leaving a horizontal line in the wall of the pit.
United States Forest Service avalanche danger advisories.
Snow fences in Switzerland during summer.
Avalanche blasting in French ski resort Tignes (3,600 m)
Avalanche warning sign near Banff, Alberta
Radar station for avalanche monitoring in Zermatt.

An avalanche is a rapid flow of snow down a slope, such as a hill or mountain.


Elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock.

Mount Everest, Earth's highest mountain
Mount Fuji, Japan's highest mountain
Mount Kilimanjaro in Tanzania, Africa's highest mountain
Peaks of Mount Kenya
Mount Elbrus, the highest mountain in Russia and Europe
Puncak Jaya in Indonesia, the highest mountain in Oceania
Geological cross-section of Fuji volcano
Illustration of mountains that developed on a fold that has been thrusted
Pirin Mountain, Bulgaria, part of the fault-block Rila-Rhodope massif
The Catskills in Upstate New York represent an eroded plateau.
A combination of high latitude and high altitude makes the northern Urals in picture to have climatic conditions that make the ground barren.
Mount Siguniang, Sichuan, China
An alpine mire in the Swiss Alps
The city of La Paz reaches up to 4000 m in elevation.
Mountaineers climbing in South Tyrol
Chimborazo, Ecuador. The point on Earth's surface farthest from its centre.

As the altitude increases, the main form of precipitation becomes snow and the winds increase.

Alpine skiing

Alpine skiers
Alpine ski slope in the Zillertal valley, Austria
Alpine ski slopes in San Carlos de Bariloche (Argentina)
Four groups of different ski types, from left to right: 
1. Non-sidecut: cross-country, telemark and mountaineering 
2. Parabolic 
3. Twin-tip 
4. Powder
Marcel Hirscher competing in the combined slalom at the World Championships in 2017
Ski trails are measured by percent slope, not degree angle. (North America)
European piste rating system (blue, red, black)

Alpine skiing, or downhill skiing, is the pastime of sliding down snow-covered slopes on skis with fixed-heel bindings, unlike other types of skiing (cross-country, Telemark, or ski jumping), which use skis with free-heel bindings.


Traditional snowshoe maker, c. 1900-1930
Plains Ojibwa performing a snowshoe dance. Drawing by George Catlin
16th century depiction of Swedish traveler with both horse and man wearing snowshoes
Teardrop snowshoes and Bearpaw snowshoes in the Gatineau Park
Canadian couple snowshoeing in 1907
Snowshoeing in Kerava, Finland in March 2011
Properly adjusted bindings on two snowshoes of different size. Note use of gaiters.
Underside of a modern fixed-rotation binding snowshoe, showing cleats for traction on steep slopes
MSR solid plastic snowshoes
Snowshoers in Bryce Canyon
Some modern snowshoes have bars that can be flipped up for ascending steep slopes. The wearer's heel can rest on the bar.
A broken snowshoe trail
A young snowshoer with a wild bird
A snowshoer packing downhill skis
Rawhide webbing

Snowshoes are specialized outdoor gear for walking over snow.


Measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that reflects all incident radiation.

The percentage of diffusely reflected sunlight relative to various surface conditions
2003–2004 mean annual clear-sky and total-sky albedo

This has been a concern since arctic ice and snow has been melting at higher rates due to higher temperatures, creating regions in the arctic that are notably darker (being water or ground which is darker color) and reflects less heat back into space.

Water cycle

Biogeochemical cycle that describes the continuous movement of water on, above and below the surface of the Earth.

Time-mean precipitation and evaporation as a function of latitude as simulated by an aqua-planet version of an atmospheric GCM (GFDL's AM2.1) with a homogeneous “slab-ocean” lower boundary (saturated surface with small heat capacity), forced by annual mean insolation.
Global map of annual mean evaporation minus precipitation by latitude-longitude
Relationship between impervious surfaces and surface runoff
Diagram of the water cycle
Natural water cycle

Precipitation: Condensed water vapor that falls to the Earth's surface. Most precipitation occurs as rain, but also includes snow, hail, fog drip, graupel, and sleet. Approximately 505000 km3 of water falls as precipitation each year, 398000 km3 of it over the oceans. The rain on land contains 107000 km3 of water per year and a snowing only 1000 km3. 78% of global precipitation occurs over the ocean.


Thundersnow formation with an occluded front
A large squall producing heavy snow and frequent lightning over Buffalo, NY.

Thundersnow, also known as a winter thunderstorm or a thundersnowstorm, is a kind of thunderstorm with snow falling as the primary precipitation instead of rain.


A hybrid Frontal-Lake Effect Snowsquall hitting Toronto, Canada during rush hour.
Frontal snowsquall moving toward Boston, Massachusetts, United States
Rapidly deteriorating weather conditions during snowsqualls often lead to traffic accidents.
Winter conditions on Ontario Highway 401 in Toronto due to a snowsquall.

A snowsquall, or snow squall, is a sudden moderately heavy snowfall with blowing snow and strong, gusty surface winds.


Scientific study of the movement, distribution, and management of water on Earth and other planets, including the water cycle, water resources, and environmental watershed sustainability.

Rain over a Scottish catchment. Understanding the cycling of water into, through, and out of catchments is a key element of hydrology.
The Roman aqueduct at Caesarea Maritima, bringing water from the wetter Carmel mountains to the settlement.
Building a map of groundwater contours
A flood hydrograph showing stage for the Shawsheen River at Wilmington.
A standard NOAA rain gauge
Estimates of changes in water storage around the Tigris and Euphrates Rivers, measured by NASA's GRACE satellites. The satellites measure tiny changes in gravitational acceleration, which can then be processed to reveal movement of water due to changes in its total mass.
Plan view of water flow through a catchment simulated by the SHETRAN hydrological modelling system.

Many of the variables constituting the terrestrial water balance, for example surface water storage, soil moisture, precipitation, evapotranspiration, and snow and ice, are measurable using remote sensing at various spatial-temporal resolutions and accuracies.