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Slush
Slush, also called slush ice, is a slurry mixture of small ice crystals (e.g. snow) and liquid water. In the natural environment, slush forms when ice or snow melts or during mixed precipitation. This often mixes with dirt and other pollutants on the surface, resulting in a gray or muddy brown color. Often, solid ice or snow can block the drainage of fluid water from slushy areas, so slush often goes through multiple freeze/thaw cycles before being able to completely drain and disappear. In areas where road salt is used to clear roadways, slush forms at lower temperatures in salted areas than it would ordinarily. This can produce a number of different consistencies over the same geographical area with scattered salted areas covered with slush and others covered with frozen precipitation. Hazards Because slush behaves like a non-Newtonian fluid, which means it behaves like a mostly solid mass until its inner shear forces rise beyond a specific threshold and beyond can ve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Munich Air Disaster
The Munich air disaster occurred on 6 February 1958, when British European Airways Flight 609 crashed on its third attempt to take off at Munich-Riem Airport in Munich, West Germany. The aircraft was carrying the Manchester United F.C., Manchester United association football, football team, nicknamed the "Busby Babes", along with supporters and journalists. There were 44 people on board, 20 of whom died at the scene. The injured, some unconscious, were taken to Munich's Rechts der Isar Hospital, where three more died, resulting in 23 fatalities, with 21 survivors. The Manchester United team were returning from a 1957–58 European Cup, European Cup match in Belgrade, Yugoslavia (now Serbia), having eliminated Red Star Belgrade to advance to the semi-finals of the competition. The flight stopped to refuel in Munich, because a non-stop flight from Belgrade to Manchester was beyond the range of the "Elizabethan"-class Airspeed Ambassador. After refuelling, pilots James Thain and K ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rain And Snow Mixed
Rain and snow mixed (American English) or sleet (Commonwealth English) is precipitation composed of a mixture of rain and partially melted snow. Unlike ice pellets, which are hard, and freezing rain, which is fluid until striking an object where it fully freezes, this precipitation is soft and translucent, but it contains some traces of ice crystals from partially fused snowflakes, also called slush. In any one location, it usually occurs briefly as a transition phase from rain to snow or vice-versa, but hits the surface before fully transforming. Its METAR code is RASN or SNRA. Terminology This precipitation type is commonly known as sleet in most Commonwealth countries. However, the United States National Weather Service uses the term ''sleet'' to refer to ice pellets instead. Formation This precipitation occurs when the temperature in the lowest part of the atmosphere is slightly above the freezing point of water The depth of low-level warm air (below the freezing leve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avalanche
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] |
Shear Force
In solid mechanics, shearing forces are unaligned forces acting on one part of a Rigid body, body in a specific direction, and another part of the body in the opposite direction. When the forces are Collinearity, collinear (aligned with each other), they are called ''tension forces'' or ''compression forces''. Shear force can also be defined in terms of Plane (geometry), planes: "If a plane is passed through a body, a force acting along this plane is called a ''shear force'' or ''shearing force''." Force required to shear steel This section calculates the force required to cut a piece of material with a shearing action. The relevant information is the area of the material being sheared, i.e. the area across which the shearing action takes place, and the shear strength of the material. A round bar of steel is used as an example. The shear strength is calculated from the tensile strength using a factor which relates the two strengths. In this case 0.6 applies to the example steel, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snow Or Ice Weather Phenomena
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 sublimate away. 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 clima ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Federal Highway Administration
The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program and the Federal Lands Highway Program. Its role had previously been performed by the Office of Road Inquiry, Office of Public Roads and the Bureau of Public Roads. History Background With the coming of the bicycle in the 1890s, interest grew regarding the improvement of streets and roads in America. The traditional method of putting the burden on maintaining roads on local landowners was increasingly inadequate. In 1893, the federal Office of Road Inquiry (ORI) was founded; in 1905, it was renamed the Office of Public Roads (OPR) and made a division of the United States Department of Agriculture. Demands grew for local and state government to take charge. With the coming of the automobile, urgent efforts were made to upgrade and moderniz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Braking Distance
A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction. Background Most brakes commonly use friction between two surfaces pressed together to convert the kinetic energy of the moving object into heat, though other methods of energy conversion may be employed. For example, regenerative braking converts much of the energy to electrical energy, which may be stored for later use. Other methods convert kinetic energy into potential energy in such stored forms as pressurized air or pressurized oil. Eddy current brakes use magnetic fields to convert kinetic energy into electric current in the brake disc, fin, or rail, which is converted into heat. Still other braking methods even transform kinetic energy into different forms, for example by transferring the energy to a rotating flywheel. Brakes are generally a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Runway
In aviation, a runway is an elongated, rectangular surface designed for the landing and takeoff of an aircraft. Runways may be a human-made surface (often asphalt concrete, asphalt, concrete, or a mixture of both) or a natural surface (sod, grass, soil, dirt, gravel, ice, sand or road salt, salt). Runways, taxiways and Airport apron, ramps, are sometimes referred to as "tarmac", though very few runways are built using Tarmacadam, tarmac. Takeoff and landing areas defined on the surface of water for seaplanes are generally referred to as waterways. Runway lengths are now International Civil Aviation Organization#Use of the International System of Units, commonly given in meters worldwide, except in North America where feet are commonly used. History In 1916, in a World War I war effort context, the first concrete-paved runway was built in Clermont-Ferrand in France, allowing local company Michelin to manufacture Bréguet Aviation military aircraft. In January 1919, aviation p ... [...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] |
Viscosity
Viscosity is a measure of a fluid's rate-dependent drag (physics), resistance to a change in shape or to movement of its neighboring portions relative to one another. For liquids, it corresponds to the informal concept of ''thickness''; for example, syrup has a higher viscosity than water. Viscosity is defined scientifically as a force multiplied by a time divided by an area. Thus its SI units are newton-seconds per metre squared, or pascal-seconds. Viscosity quantifies the internal friction, frictional force between adjacent layers of fluid that are in relative motion. For instance, when a viscous fluid is forced through a tube, it flows more quickly near the tube's center line than near its walls. Experiments show that some stress (physics), stress (such as a pressure difference between the two ends of the tube) is needed to sustain the flow. This is because a force is required to overcome the friction between the layers of the fluid which are in relative motion. For a tube ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
