9
$\begingroup$

I was reading about gigantic storms on giant gas planets, the great red spot on Jupiter and hexagon on Saturn to name a few, how about our Sun which is consist of plasma(hot gas which have some of their electrons stripped) why don't we see any big hurricane?

$\endgroup$
  • 1
    $\begingroup$ It's very hot and dry up there, and they don't get a lot of rain. :) $\endgroup$ – PM 2Ring Nov 10 '17 at 11:17
11
$\begingroup$

We see sunspots, which are giant, planet-sized storms on the surface of the Sun. There are however many differences between sunspots, the Great Red Spot on Jupiter, and tropical cyclones (e.g., hurricanes) on the Earth. Tropical cyclones are low pressure systems fueled by evaporation of warm ocean water and sustained by the Earth's somewhat rapid rotation rate. The Great Red Spot is a high pressure system that is sustained by Jupiter's quite rapid rotation rate. Sunspots are low temperature systems fueled by the Sun's magnetic field and carried along by the Sun's rather low rotation rate.

$\endgroup$
9
$\begingroup$

In addition to the answer above, spiraling storms like hurricanes or the great red spot, are quite orderly and require the right conditions and energy transfer. The great red spot keeps relatively consistent latitude and it's been there for centuries, so it's obviously stable and ordered, though it may be shrinking. The cause of the great red spot isn't known, but efficient heat transfer of Jupiter's vast internal heat, and the principal of hot internal gas rising and cool surface gas falling and Jupiter's very strong Coriolis effect likely helped create and maintain it.

For hurricanes on Earth, a few specific things to happen. There needs to be an energy source to sustain them, which is why they only form over warm oceans, mostly during the summer and fall seasons when oceans are warmest. The rapid evaporation of warm ocean water feeds the hurricane and the condensation of that evaporated water vapor in the upper atmosphere, drives the low pressure system. The spiral is the most efficient form of heat transfer and of light air rising/warm air falling. The high speed surface winds increase the evaporation rate over the ocean, so once the spiral forms and stabilizes, it's self sustaining, until it drifts over colder water or land. Hurricanes are orderly with very efficient heat transfer and ordered layers of rising and falling air.

enter image description here

Over 90% of tropical depressions don't become hurricanes. Generally speaking, a perpendicular direction between the cool air above and the warm air below is required to get the spiraling wind started. That's partly why the IPCC has previously predicted a possible decrease in hurricane formation, because the formative conditions need to be just right and a more turbulent upper atmosphere might decrease hurricane formation even though the warmer oceans works in the opposite direction. All this was footnoted with some uncertainty and predicting changes in wind direction is tricky, so it shouldn't be held against the IPCC. The point is, Hurricanes need the right balance. They don't form easily, though once formed they tend to stabilize and grow, until they drift off the warm ocean water that feeds them.

Air is also quite light, and the heat energy transfer of water's phase change is significant enough to create the 100 plus mph winds in an orderly spiral. On both Jupiter and Earth the right conditions are met for large, high wind speed, spiral storm formation. Like Earth, Jupiter also has clouds and rain, both water and ammonia, which likely assist in it's heat transfer by phase change (though I'm nowhere near smart enough to say how much that contributes regarding Jupiter's red spot, on Earth the phase change of water is essential for hurricane formation. Without abundant warm surface water - no hurricane.

The sun, by comparison, is all plasma. There's no phase change that efficiently increases the transition of heat and energy, though there are probably variations in ionization, but I'll get to that later. The Sun's surface is also quite chaotic and it has magnetic storms, making the neat birth of a spiral storm by perpendicular wind gusts one above the other, less likely.

Magnetic storms are twisted and I don't want to say that nothing spirals or twists on the surface of the sun, because that's not true. But the magnetic storms on the surface of the sun aren't like the neat and tidy cone shaped spirals of hurricanes. They reach well above the sun's atmosphere, not in the atmosphere, and the shape is different.

enter image description here

Finally, the material that makes up the Sun's transition region or "atmosphere" isn't good for hurricane formation. To quote from Wikipedia:

Below, most of the helium is not fully ionized, so that it radiates energy very effectively; above, it becomes fully ionized. This has a profound effect on the equilibrium temperature (see below).

Below, the material is opaque to the particular colors associated with spectral lines, so that most spectral lines formed below the transition region are absorption lines in infrared, visible light, and near ultraviolet, while most lines formed at or above the transition region are emission lines in the far ultraviolet (FUV) and X-rays. This makes radiative transfer of energy within the transition region very complicated.

Below, gas pressure and fluid dynamics usually dominate the motion and shape of structures; above, magnetic forces dominate the motion and shape of structures, giving rise to different simplifications of magnetohydrodynamics.

The transition region itself is not well studied in part because of the computational cost, . . .

Hurricanes could theoretically form as a result of fluid dynamics, but the rapid rate that partially ionized helium radiates heat makes the formation of large circulating structures, which are basically engines of convection, impractical and unnecessary. There's no need for efficient convection when the energy transfer is very efficient by radiation.

The Sun's atmosphere isn't like the atmosphere of the Earth and in the upper layers of Jupiter where the atmosphere is fairly effective and holding onto it's heat (We wouldn't have warm and cold fronts if it wasn't). Those regions of warm and cold air that mostly maintain their temperature drive the convective process. You need jets of warm and cold air to flow past each other in a hurricane. The Sun's efficient radiation of partially ionized helium works against that principal.

There's also a relatively low Coriolis effect on the surface of the sun, which assists with the formation of hurricanes.

In short, the conditions are not at all right. The Sun's turbulence, it's relatively low rotation rate, no phase-change to feed the system and it's partially ionized helium in it's lower "atmosphere", all work against the formation of spiraling, cone shaped, high speed wind systems.

On Brown dwarfs with much cooler surface temperatures, hurricanes might be entirely possible. The math behind atmospheric convection mechanisms is complicated, so this is more of a general explanation but the Sun isn't a good candidate for hurricanes on many levels.

$\endgroup$
  • $\begingroup$ This one should be the Answer. $\endgroup$ – Jhollman Feb 11 at 20:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.