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Most lakes in the world occupy basins scoured out by glaciers. Glacial motion can be fast (up to 30 metres per day (98 ft/d), observed on Jakobshavn Isbræ in Greenland) [1] or slow (0.5 metres per year (20 in/year) on small glaciers or in the center of ice sheets), but is typically around 25 centimetres per day (9.8 in/d). [2]
Snow fences work by inducing turbulence in the wind, forcing it to drop much of its snow load near the fence. Bridge supports (piers) in water. When river flow is slow, water flows smoothly around the support legs. When the flow is faster, a higher Reynolds number is associated with the flow.
The limiting case of the Venturi effect is when a fluid reaches the state of choked flow, where the fluid velocity approaches the local speed of sound of the fluid. When a fluid system is in a state of choked flow, a further decrease in the downstream pressure environment will not lead to an increase in velocity, unless the fluid is compressed.
The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid behind the obstacle flows into the void creating a swirl of fluid on each edge of the obstacle, followed by a short reverse flow of fluid behind the obstacle flowing upstream, toward the back of the obstacle.
For lake-effect rain or snow to form, the air moving across the lake must be significantly cooler than the surface air (which is likely to be near the temperature of the water surface). Specifically, the air temperature at an altitude where the air pressure is 850 millibars (85 kPa ) (roughly 1.5 kilometers or 5,000 feet vertically) should be ...
= is the escape velocity, and β e = v e / c {\displaystyle \beta _{e}=v_{e}/c} is the escape velocity, expressed as a fraction of the speed of light c. To illustrate then, without accounting for the effects of rotation, proximity to Earth's gravitational well will cause a clock on the planet's surface to accumulate around 0.0219 fewer seconds ...
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, mudslides, rock slides, and serac collapses.
[31] [32] Microbial growth, such as snow algae on glaciers and ice algae on sea ice can also cause a snow darkening effect. [33] Melting caused by algae increases the presence of liquid water in snow and ice surfaces, which then stimulates the growth of more snow and ice algae and causes a decrease in albedo, forming a positive feedback. [30]