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Avalanches
An avalanche is a rapid flow of snow down a Grade (slope), slope, such as a hill or mountain. Avalanches can be triggered spontaneously, by factors such as increased precipitation or snowpack weakening, or by external means such as humans, other animals, and earthquakes. Primarily composed of flowing snow and air, large avalanches have the capability to capture and move ice, rocks, and trees. Avalanches occur in two general forms, or combinations thereof: slab avalanches made of tightly packed snow, triggered by a collapse of an underlying weak snow layer, and loose snow avalanches made of looser snow. After being set off, avalanches usually accelerate rapidly and grow in mass and volume as they capture more snow. If an avalanche moves fast enough, some of the snow may mix with the air, forming a powder snow avalanche. Though they appear to share similarities, avalanches are distinct from slush flows, Mudflow, mudslides, Landslide#Debris landslide, rock slides, and serac collap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avalanche Control
Avalanche control or avalanche defense activities reduce the hazard avalanches pose to human life, activity, and property."Mitigation and Land Use - Avalanches" , Colorado Geological Survey Avalanche control begins with a risk assessment conducted by surveying for potential avalanche terrain by identifying geographic features such as vegetation patterns, drainages, and seasonal snow distribution that are indicative of avalanches. From the identified avalanche risks, the hazard is assessed by identifying threatened human geographic features such as roads, ski-hills, and buildings. Avalanche control programs address the avalanche hazard by formulating prevention and mitigation plans, which are then executed during the winter season. The prevention and mitigation plans combine extensive snow pack observation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slush Flow
A slushflow is rapid mass movement of water and snow, and is categorized as a type of debris flow. Slushflows are caused when water reaches a critical concentration in the snowpack due to more water inflow than outflow. The high water concentration weakens the cohesion of the snow crystals and increases the weight of the snowpack. A slushflow is released when the component of the force of gravity parallel to the slope generates a hydraulic pressure gradient exceeding the tensile strength and basal friction of the snowpack. While frequently compared to an avalanche, they have some key differences. Slushflows are lower in frequency than avalanches, have higher water content, are more laminar in flow, and have lower velocity. They most commonly occur at higher latitudes in the winter during high precipitation and in the spring during high snowmelt. Because of their high water content, they can flow down gentle slopes of only a few degrees at low altitudes. They are a significant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snow
Snow consists of 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. It consists of 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 Sublimation (phase transition), sublimate away. Snowstorms organize and develop by feeding on sources of atmospheric moisture and cold air. Snowflakes Nucleation, nucleate around particles in the atmosphere by attracting supercooling, supercooled water droplets, which Freezing, freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles, columns, and Hard rime, rime. As snow accumulates into a snowpack, it may blow into drifts. Over time, accumulated snow m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Hazard
A natural disaster is the very harmful impact on a society or community brought by natural phenomenon or hazard. Some examples of natural hazards include avalanches, droughts, earthquakes, floods, heat waves, landslides - including submarine landslides, tropical cyclones, volcanic activity and wildfires. Additional natural hazards include blizzards, dust storms, firestorms, hails, ice storms, sinkholes, thunderstorms, tornadoes and tsunamis. A natural disaster can cause loss of life or damage property. It typically causes economic damage. How bad the damage is depends on how well people are prepared for disasters and how strong the buildings, roads, and other structures are. Scholars have argued the term "natural disaster" is unsuitable and should be abandoned. Instead, the simpler term ''disaster'' could be used. At the same time, the type of hazard would be specified. A disaster happens when a natural or human-made hazard impacts a vulnerable community. It r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowboarder Triggered Soft Slab Near Mount Baker
Snowboarding is a recreational and competitive activity that involves descending a snow-covered surface while standing on a snowboard that is almost always attached to a rider's feet. It features in the Winter Olympic Games and Winter Paralympic Games. Snowboarding was developed in the United States, inspired by skateboarding, sledding, surfing, and skiing. It became popular around the world and was introduced as a Winter Olympic Sport at Nagano in 1998 and featured in the Winter Paralympics at Sochi in 2014. , its popularity (as measured by equipment sales) in the United States peaked in 2007 and has been in a decline since. History The first snowboards were developed in 1965 when Sherm Poppen, an engineer in Muskegon, Michigan, invented a toy for his daughters by fastening two skis together and attaching a rope to one end so he would have some control as they stood on the board and glided downhill. Dubbed the "snurfer" (combining snow and surfer) by his wife Nancy, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Powder Snow Avalanche
thumbnail, Example of powder snow avalanche A powder snow avalanche is a type of avalanche where snow grains are largely or completely suspended and moved by air in a state of fluid turbulence. They are particle-laden gravity currents and closely related to turbidity currents, pyroclastic flows from volcanoes and dust storms in the desert. The turbulence is typically generated by the forward motion of the current along the lower boundary of the domain, the motion being in turn driven by the action of gravity on the density difference between the particle-fluid mixture and the ambient fluid. The ambient fluid is generally of similar composition to (and miscible with) the interstitial fluid, and is water for turbidity currents and air for avalanches. These flows are non-conservative in that they may exchange particles at the lower boundary by deposition or suspension, and may exchange fluid with the ambient by entrainment or detrainment. Such flows dissipate when the turbule ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snowpack
Snowpack is an accumulation of snow that compresses with time and melts seasonally, often at high elevation or high latitude. Snowpacks are an important water resource that feed streams and rivers as they melt, sometimes leading to flooding. Snowpacks provide water to down-slope communities for drinking and agriculture. High-latitude or high-elevation snowpacks contribute mass to glaciers in their accumulation zones, where annual snow deposition exceeds annual melting. Assessing the formation and stability of snowpacks is important in the study and prediction of avalanches. Scientists study the physical properties of snow under different conditions and their evolution, and more specifically snow metamorphism, snow hydrology (that is, the contribution of snow melt to catchment hydrology), the evolution of snow cover with climate change and its effect on the ice–albedo feedback and hydrology, both on the ground and by using remote sensing. Snow is also studied in a more global c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Khumbu Icefall
The Khumbu Icefall is located at the head of the Khumbu Glacier and the foot of the Western Cwm. It lies at an elevation of on the Nepali slopes of Mount Everest, not far above Base Camp and southwest of the summit. The icefall is regarded as one of the most dangerous sections of the South Col route to Everest's summit. Overview The Khumbu Glacier moves an estimated down the flank of Mt. Everest every day. Ice entering the fall takes approximately 4.3 years to emerge at the base, which is lower and away horizontally. The speed of ice flow and the precipitous elevation drop create a bergschrund (ice berg shoulder), characterized at the top by massive transverse blocks that calve off the upper glacier, creating gaping crevasse A crevasse is a deep crack that forms in a glacier or ice sheet. Crevasses form as a result of the movement and resulting stress associated with the shear stress generated when two semi-rigid pieces above a plastic substrate have different rate ... ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wind Slabs
Wind is the natural movement of air or other gases relative to a planet's surface. Winds occur on a range of scales, from thunderstorm flows lasting tens of minutes, to local breezes generated by heating of land surfaces and lasting a few hours, to global winds resulting from the difference in absorption of solar energy between the climate zones on Earth. The study of wind is called anemology. The two main causes of large-scale atmospheric circulation are the differential heating between the equator and the poles, and the rotation of the planet (Coriolis effect). Within the tropics and subtropics, thermal low circulations over terrain and high plateaus can drive monsoon circulations. In coastal areas the sea breeze/land breeze cycle can define local winds; in areas that have variable terrain, mountain and valley breezes can prevail. Winds are commonly classified by their spatial scale, their speed and direction, the forces that cause them, the regions in which they occur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sunlight
Sunlight is the portion of the electromagnetic radiation which is emitted by the Sun (i.e. solar radiation) and received by the Earth, in particular the visible spectrum, visible light perceptible to the human eye as well as invisible infrared (typically perceived by humans as warmth) and ultraviolet (which can have physiological effects such as sunburn) lights. However, according to the American Meteorological Society, there are "conflicting conventions as to whether all three [...] are referred to as light, or whether that term should only be applied to the visible portion of the spectrum." Upon reaching the Earth, sunlight is light scattering by particles, scattered and attenuation, filtered through the atmosphere of Earth, Earth's atmosphere as daylight when the Sun is above the horizon. When direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat (atmospheric). When cloud cover, blocked by clouds or dif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Patagonia
Patagonia () is a geographical region that includes parts of Argentina and Chile at the southern end of South America. The region includes the southern section of the Andes mountain chain with lakes, fjords, temperate rainforests, and glaciers in the west and Patagonian Desert, deserts, Plateaus, tablelands, and steppes to the east. Patagonia is bounded by the Pacific Ocean on the west, the Atlantic Ocean to the east, and many bodies of water that connect them, such as the Strait of Magellan, the Beagle Channel, and the Drake Passage to the south. The northern limit of the region is not precisely defined; the Colorado River, Argentina, Colorado and Barrancas River, Barrancas rivers, which run from the Andes to the Atlantic, are commonly considered the northern limit of Argentine Patagonia. The archipelago of Tierra del Fuego is sometimes considered part of Patagonia. Most geographers and historians locate the northern limit of Chilean Patagonia at Huincul Fault, in Araucanía R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
