by neufer » Mon Apr 03, 2017 12:38 pm
somebodyshort wrote:
If you boil water at certain depths in a pan you get the same hexagonal patern
Those are non-rotating Rayleigh–Bénard convection cells with warm centers.
https://en.wikipedia.org/wiki/Rayleigh%E2%80%93B%C3%A9nard_convection wrote:
<<Rayleigh–Bénard convection is a type of natural convection, occurring in a plane horizontal layer of fluid heated from below, in which the fluid develops a regular pattern of convection cells known as Bénard cells. Rayleigh–Bénard convection is one of the most commonly studied convection phenomena because of its analytical and experimental accessibility. The convection patterns are the most carefully examined example of self-organizing nonlinear systems. Buoyancy, and hence gravity, is responsible for the appearance of convection cells. The initial movement is the upwelling of lesser density fluid from the heated bottom layer. This upwelling spontaneously organizes into a regular pattern of cells.>>
Todays APOD shows rotating Rossby waves around a cold center.
Our slowly rotating Earth produces Rossby waves that are less stable than on rapidly spinning Saturn:
https://en.wikipedia.org/wiki/Rossby_wave wrote:
<<Atmospheric Rossby waves result from the conservation of potential vorticity and are influenced by the Coriolis force and pressure gradient. A fluid, on the Earth, that moves toward the pole will deviate toward the east; a fluid moving toward the equator will deviate toward the west (true in either hemisphere). The deviations are caused by the Coriolis force and conservation of potential vorticity which leads to changes of relative vorticity. This is analogous to conservation of angular momentum in mechanics. In planetary atmospheres, including Earth, Rossby waves are due to the variation in the Coriolis effect with latitude. Carl-Gustaf Arvid Rossby first identified such waves in the Earth's atmosphere in 1939 and went on to explain their motion.>>
[quote="somebodyshort"]
If you boil water at certain depths in a pan you get the same hexagonal patern[/quote]
[c]Those are [size=150][b][u][color=#FF00FF]non[/color]-rotating[/u][/b][/size] Rayleigh–Bénard convection cells with [size=150][b][u][color=#FF0000]warm centers[/color][/u][/b][/size].[/c]
[quote=" https://en.wikipedia.org/wiki/Rayleigh%E2%80%93B%C3%A9nard_convection"]
<<Rayleigh–Bénard convection is a type of natural convection, occurring in a plane horizontal layer of fluid heated from below, in which the fluid develops a regular pattern of convection cells known as Bénard cells. Rayleigh–Bénard convection is one of the most commonly studied convection phenomena because of its analytical and experimental accessibility. The convection patterns are the most carefully examined example of self-organizing nonlinear systems. Buoyancy, and hence gravity, is responsible for the appearance of convection cells. The initial movement is the upwelling of lesser density fluid from the heated bottom layer. This upwelling spontaneously organizes into a regular pattern of cells.>>[/quote]
[c]Todays APOD shows[size=150] [b][u]rotating[/u][/b][/size] Rossby waves around a [size=150][b][u][color=#0000FF]cold center[/color][/u][/b][/size].
Our [b][u]slowly rotating[/u][/b] Earth produces Rossby waves that are less stable than on [b][u]rapidly spinning[/u][/b] Saturn:[/c]
[quote=" https://en.wikipedia.org/wiki/Rossby_wave"]
[float=right][img3="[b][color=#0000FF]Meanders of the northern hemisphere's jet stream developing (a, b)
and finally detaching a "drop" of cold air (c).
Orange: warmer air; pink: jet stream; blue: colder air.[/color][/b]"]https://upload.wikimedia.org/wikipedia/commons/thumb/7/72/Jetstream_-_Rossby_Waves_-_N_hemisphere.svg/1042px-Jetstream_-_Rossby_Waves_-_N_hemisphere.svg.png[/img3][/float]<<Atmospheric Rossby waves result from the conservation of potential vorticity and are influenced by the Coriolis force and pressure gradient. A fluid, on the Earth, that moves toward the pole will deviate toward the east; a fluid moving toward the equator will deviate toward the west (true in either hemisphere). The deviations are caused by the Coriolis force and conservation of potential vorticity which leads to changes of relative vorticity. This is analogous to conservation of angular momentum in mechanics. In planetary atmospheres, including Earth, Rossby waves are due to the variation in the Coriolis effect with latitude. Carl-Gustaf Arvid Rossby first identified such waves in the Earth's atmosphere in 1939 and went on to explain their motion.>>[/quote]