by neufer » Mon Jul 26, 2021 3:03 pm
Chris Peterson wrote: ↑Sun Jul 25, 2021 12:39 pm
De58te wrote: ↑Sun Jul 25, 2021 8:05 am
Another fun fact. Neptune has the fastest winds in the Solar System. They can whip past you at twice the speed of sound! Which means if you happen to be on Neptune you'll never hear the wind blowing before it tears you apart like if you fell into a tornado. At least on Earth you can hear the tornado coming.
Bulk air movement in the upper atmosphere may exceed the speed of sound on Earth (but not necessarily the local speed of sound). If there's a tornado on Neptune, you'll hear it coming.
Bulk air movement can
NEVER exceed the local speed of sound because
it is the air, itself, that carries the sound waves.
If you are downstream of a tornado (or a dark spot hurricane), you'll hear it coming; however, the storms may not be able to "hear" you. (And if you are upstream you have nothing to worry about).
In any event, the retrograde equatorial winds nearly reach supersonic velocity only with respect to Neptune's fixed magnetic field lines which the winds presumably ignore.
https://en.wikipedia.org/wiki/Neptune#Climate wrote:
<<Because Neptune is not a solid body, its atmosphere undergoes differential rotation. The wide equatorial zone rotates with a period of about 18 hours (2,400 m/s), which is slower than the 16.1-hour rotation of the planet's magnetic field (2,685 m/s). By contrast, the reverse is true for the polar regions where the rotation period is 12 hours. This differential rotation is the most pronounced of any planet in the Solar System, and it results in strong latitudinal wind shear.
Neptune's weather is characterised by extremely dynamic storm systems, with winds reaching speeds of almost 600 m/s—nearly reaching supersonic flow [with respect to Neptune's fixed magnetic field lines]. Most of the winds on Neptune move in a direction opposite the planet's rotation. The general pattern of winds showed prograde rotation at high latitudes vs. retrograde rotation at lower latitudes. The difference in flow direction is thought to be a "skin effect" and not due to any deeper atmospheric processes.
The abundance of methane, ethane and acetylene at Neptune's equator is 10–100 times greater than at the poles. This is interpreted as evidence for upwelling at the equator and subsidence near the poles because photochemistry cannot account for the distribution without meridional circulation.>>
[quote="Chris Peterson" post_id=315275 time=1627216766 user_id=117706]
[quote=De58te post_id=315273 time=1627200352 user_id=141631]
Another fun fact. Neptune has the fastest winds in the Solar System. They can whip past you at twice the speed of sound! Which means if you happen to be on Neptune you'll never hear the wind blowing before it tears you apart like if you fell into a tornado. At least on Earth you can hear the tornado coming.[/quote]
Bulk air movement in the upper atmosphere may exceed the speed of sound on Earth (but not necessarily the local speed of sound). If there's a tornado on Neptune, you'll hear it coming.[/quote]
[float=left][img3=Shock waves produced by a T-38 Talon during flight]https://upload.wikimedia.org/wikipedia/commons/6/65/Shockwave_pattern_around_a_T-38C_observed_with_Background-Oriented_Schlieren_photography_%281%29.jpg[/img3][/float]
Bulk air movement can [b][u][color=#0000FF]NEVER[/color][/u][/b] exceed the local speed of sound because [b][u][color=#0000FF]it is the air, itself, that carries the sound waves[/color][/u][/b].
If you are downstream of a tornado (or a dark spot hurricane), you'll hear it coming; however, the storms may not be able to "hear" you. (And if you are upstream you have nothing to worry about).
In any event, the retrograde equatorial winds nearly reach supersonic velocity only with respect to Neptune's fixed magnetic field lines which the winds presumably ignore.
[quote=https://en.wikipedia.org/wiki/Neptune#Climate]
<<Because Neptune is not a solid body, its atmosphere undergoes differential rotation. The wide equatorial zone rotates with a period of about 18 hours (2,400 m/s), which is slower than the 16.1-hour rotation of the planet's magnetic field (2,685 m/s). By contrast, the reverse is true for the polar regions where the rotation period is 12 hours. This differential rotation is the most pronounced of any planet in the Solar System, and it results in strong latitudinal wind shear.
Neptune's weather is characterised by extremely dynamic storm systems, with winds reaching speeds of almost 600 m/s—nearly reaching supersonic flow [with respect to Neptune's fixed magnetic field lines]. Most of the winds on Neptune move in a direction opposite the planet's rotation. The general pattern of winds showed prograde rotation at high latitudes vs. retrograde rotation at lower latitudes. The difference in flow direction is thought to be a "skin effect" and not due to any deeper atmospheric processes.
The abundance of methane, ethane and acetylene at Neptune's equator is 10–100 times greater than at the poles. This is interpreted as evidence for upwelling at the equator and subsidence near the poles because photochemistry cannot account for the distribution without meridional circulation.>>[/quote]