The strange storms on Jupiter

Posted: September 26, 2020 by oldbrew in Maths, research, solar system dynamics, wind
Tags: ,

Cyclones in Jupiter’s atmosphere [image credit: NASA]


At the south pole of Jupiter lurks a striking sight—even for a gas giant planet covered in colorful bands that sports a red spot larger than the Earth, says Phys.org.

Down near the south pole of the planet, mostly hidden from the prying eyes of humans, is a collection of swirling storms arranged in an unusually geometric pattern.

Since they were first spotted by NASA’s Juno space probe in 2019, the storms have presented something of a mystery to scientists.

The storms are analogous to hurricanes on Earth. However, on our planet, hurricanes do not gather themselves at the poles and twirl around each other in the shape of a pentagon or hexagon, as do Jupiter’s curious storms.

Now, a research team working in the lab of Andy Ingersoll, Caltech professor of planetary science, has discovered why Jupiter’s storms behave so strangely. They did so using math derived from a proof written by Lord Kelvin, a British mathematical physicist and engineer, nearly 150 years ago.

Ingersoll, who was a member of the Juno team, says Jupiter’s storms are remarkably similar to the ones that lash the East Coast of the United States every summer and fall, just on a much larger scale.

“If you went below the cloud tops, you would probably find liquid water rain drops, hail, and snow,” he says. “The winds would be hurricane-force winds. Hurricanes on Earth are a good analog of the individual vortices within these arrangements we see on Jupiter, but there is nothing so stunningly beautiful here.”

As on Earth, Jupiter’s storms tend to form closer to the equator and then drift toward the poles. However, Earth’s hurricanes and typhoons dissipate before they venture too far from the equator. Jupiter’s just keep going until they reach the poles.

“The difference is that on the earth hurricanes run out of warm water and they run into continents,” Ingersoll says. Jupiter has no land, “so there’s much less friction because there’s nothing to rub against. There’s just more gas under the clouds. Jupiter also has heat left over from its formation that is comparable to the heat it gets from the sun, so the temperature difference between its equator and its poles is not as great as it is on Earth.”

However, Ingersoll says, this explanation still does not account for the behavior of the storms once they reach Jupiter’s south pole, which is unusual even compared to other gas giants. Saturn, which is also a gas giant, has one enormous storm at each of its poles, rather than a geometrically arranged collection of storms.

The answer to the mystery of why Jupiter has these geometric formations and other planets do not, Ingersoll and his colleagues discovered, could be found in the past, specifically in work conducted in 1878 by Alfred Mayer, an American physicist, and Lord Kelvin.

Mayer had placed floating circular magnets in a pool of water and observed that they would spontaneously arrange themselves into geometric configurations, similar to those seen on Jupiter, with shapes that depended on the number of magnets. Kelvin used Mayer’s observations to develop a mathematical model to explain the magnets’ behavior.

“Back in the 19th century, people were thinking about how spinning pieces of fluid would arrange themselves into polygons,” Ingersoll says. “Although there were lots of laboratory studies of these fluid polygons, no one had thought of applying that to a planetary surface.”

To do so, the research team used a set of equations known as the shallow-water equations to build a computer model of what might be happening on Jupiter, and began to run simulations.

“We wanted to explore the combination of parameters that makes these cyclones stable,” says Cheng Li (Phd ’17), lead author and 51 Pegasi b postdoctoral fellow at UC Berkeley. “There are established theories that predict that cyclones tend to merge at the pole due to the rotation of the planet and that’s what we found in the initial trial runs.”

Eventually, however, the team found that a Jupiter-like stable geometric arrangement of storms would form if the storms were each surrounded by a ring of winds that turned in the opposite direction from the spinning storms, or a so-called anticyclonic ring.

The presence of anticyclonic rings causes the storms to repel each other, rather than merge.

Full article here.

Comments
  1. oldbrew says:

    Jupiter also has heat left over from its formation that is comparable to the heat it gets from the sun

    ‘heat left over’ – that old chestnut.

  2. Curious George says:

    Each storm must be surrounded by a ring of winds … I thought a storm was a ring of winds. The writer probably attended Greta’s Friday school.

  3. pochas94 says:

    Could it be that 5 is the first prime after the first non-prime? Help, PV.

  4. oldbrew says:

    pochas – the phys.org link has an animation (below) of the switch from 6 to 5, then 4, storms. But 5 is the central number as you say.

    5 and 8 (the J north pole counterpart system) are Fibonacci numbers, which could have something to do with the observed stability of the patterns, unchanged since mid-2016.

    Caption: Under some simulated conditions, and on Saturn, cyclonic storms merge with one another instead of repelling each other [Credit: California Institute of Technology]
    – – –
    Nine short video animations here, including the one above. Some don’t do much though.
    https://www.pnas.org/content/suppl/2020/09/01/2008440117.DCSupplemental

  5. oldbrew says:

    CG – this might help, or not…

    Abstract

    From its pole-to-pole orbit, the Juno spacecraft discovered arrays of cyclonic vortices in polygonal patterns around the poles of Jupiter. In the north, there are eight vortices around a central vortex, and in the south there are five. The patterns and the individual vortices that define them have been stable since August 2016. The azimuthal velocity profile vs. radius has been measured, but vertical structure is unknown. Here, we ask, what repulsive mechanism prevents the vortices from merging, given that cyclones drift poleward in atmospheres of rotating planets like Earth? What atmospheric properties distinguish Jupiter from Saturn, which has only one cyclone at each pole? We model the vortices using the shallow water equations, which describe a single layer of fluid that moves horizontally and has a free surface that moves up and down in response to fluid convergence and divergence. We find that the stability of the pattern depends mostly on shielding—an anticyclonic ring around each cyclone, but also on the depth. Too little shielding and small depth lead to merging and loss of the polygonal pattern. Too much shielding causes the cyclonic and anticyclonic parts of the vortices to fly apart. The stable polygons exist in between. Why Jupiter’s vortices occupy this middle range is unknown. The budget—how the vortices appear and disappear—is also unknown, since no changes, except for an intruder that visited the south pole briefly, have occurred at either pole since Juno arrived at Jupiter in 2016.
    [bold added]

    https://www.pnas.org/content/early/2020/09/01/2008440117

  6. Paul Vaughan says:

    unusually geometric pattern”

    Note the adjective. The author thus has not become a victim of conventional mainstream financial-terror campaigns. Submission to the behavior modification regime is saving the author — and the author’s online karma integral as measured by big tech remains above baseline. The author is thus eligible to have a job, a home, and an internet connection — while retaining a voice in society. Meanwhile the public doesn’t notice “the US-EU-well” giant geometry tide to the lower ring of “democratic” government: big tech hurricanes are well-anchored to a pole-arising pentagon. You can still vote for a government, but all IT has left is (Boris’ — not Jupiter) wind “power”.

    [mod] this comment is off topic

  7. gbaikie says:

    What about Jupiter recent impactors.
    Are pictures of it before the impactors?

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