"To be fond of reading is a mistake," says Philip Markus, a computer physicist and a coffee maker at a coffee house near the campus. Professor of the Department of Mechanical Engineering at the University of California at Berkeley. "You learn too much. That's how I sat down on the dynamics of liquids. "
This was in 1978, when Marcus worked as a Ph.D. in Cornell for the first year, specializing in numerical simulations of solar convection using spectral methods. But he wanted to study the evolution of the cosmos and the general theory of relativity; The problem, he said, was that people claimed that they had never seen the results of the UTO work in their entire life. As a result, "this area has calmed down a little, and all specialists in general relativity diverged into other areas."
It was in 1978 that Voyager 1 began to send photographs taken at close range of Jupiter to Earth. When Marcus needed, as he says, "relax, relieve stress, and all that," he went to a special laboratory near the building of astrophysics, and admired the photos of the Great Red Spot made from Voyager. The storm has already passed hundreds of millions of miles, at least since 1665, when it was first seen by Robert Hooke. "I realized that almost no one from the field of astronomy was aware of the dynamics of liquids, but I was just," he told me. "And I said – well, I have the opportunity to study this question, and it is no worse than the others."
So he has not stopped since. Today he is an expert on the most famous storm in the solar system. Possessing the mountain biker's constitution, he answers my questions, actively moving, and sometimes waving his arms in an attempt to clarify his words. He acknowledged that his energy could lead to awkwardness. "People are suspicious of me," he says. "If I go into the laboratory, I immediately break something." Fortunately, he said, "I was very fortunate to be friends with several experimenters."
What strikes you in the Great Red Spot?
A few things. People have long thought about why the Great Red Spot (OPF) has been living for so long? BKP is a storm, and we are used to earthly storms. The average hurricane lives a maximum of a couple of weeks, and the mechanism of its destruction is absolutely certain: it either passes over cold water and loses energy, or passes over the ground and sharply loses energy. The tornado is impressive, but it only lasts a few hours. So why does the BCP live so long? Previously, people said: "These are clouds that lingered at the top of the mountain." Or: "This is an iceberg in the sea of hydrogen." Similar theories once ended in 1979, when Voyagers 1 and 2 flew past the planet. Nobody knew then that this was a whirlwind, a huge hurricane, which requires six days to turn. The US would fit in the OPF couple of hundred times. It's really great. One of the remarkable achievements of Voyager's missions was that they made hundreds of photos of the clouds that make up the OPF, and we were finally able to see how this thing spins, and then we were able to say with certainty that this is a whirlwind. Before that, no one knew that it was spinning.
How did the OPF appear?
The OPF probably appeared in one of two ways. It could be an upward flow of gas, reaching the stratosphere and wrapped, which is why the vortex turned out. If the ascending stream can reach a sufficiently stable layer of the atmosphere, it can propagate horizontally, and when such a flow spreads horizontally on such a rapidly rotating system as Jupiter, this spread leads to the formation of a vortex. Another possibility is that the jet stream in the atmosphere lost stability, wave oscillations began, and when the wave amplitude increased to a certain limit, it broke up, forming small vortices, which then merged.
Why did it appear on Jupiter and not somewhere else?
On Earth, if you fly over the ocean, you can almost certainly tell where the islands will be under you, because clouds will hang over them – topographic features often attract clouds to you. But on Jupiter there is no solid surface, unless you go down to a very small core. This, in fact, a ball of liquid. There is no difference in heating between continents and islands. Winds are not interrupted by mountain ranges. There is no such thing, so there is a set of very well-organized streaming streams on it. And if you have such currents, the vortices appear naturally. Winds go in opposite directions, rub against each other. This is approximately like a bearing ball, located between two walls moving in opposite directions. The walls cause the ball to rotate, and the oppositely moving currents on Jupiter cause the air between them to rotate. The vortexes formed between the currents resist everything that they crash into. If I make a whirlpool in the bathroom and slap on it, it disappears. If I make a simulation of the OPF on Jupiter, located between zonal winds, and slap on it, trying to divide it into two parts, it will gather again. Therefore, I imagine jet streams as gardens in which vortices can be grown.
What does not physically prevent the OPF from decaying?
I think that the OPF is 50-70 km high. He has about 26,000 km across. It turns out such a pancake. Just like with a tube of toothpaste, if I push on the pancake in the center, then from its sides, and also from above and below, something will come out. It is known that in the center of the OPF is high pressure, but its gases do not get out horizontally from all sides because of the Coriolis force – they get out vertically from above and from below. So what prevents the gases from getting out from above and below? I only know one way to prevent this. On top of the OPF there is a dense cold atmosphere cap. It is this additional density that pushes the OPF gases back down. And under the BKP there must be a warm floating atmospheric bottom, which prevents high pressure in the center from pushing the gases out of the OPF downwards. This is the balance.
You can conduct numerical and analytical calculations and think: "Hmm, I wonder, how tight is the lid here? What should be the buoyancy at the bottom to achieve such a balance? "The kinetic energy is associated with the winds of the vortex, and the potential energy is connected with the cold, dense lid on top and the floating warm bottom. Most of my colleagues who study the OPF concentrate on kinetic energy, but I tell them: "No, not children, only 16% of energy is concentrated in it." Most of the energy of the OPF is the potential energy of a dense cold cover and a warm floating bottom. If you want to stay awake at night thinking about what can attack the OPF, then reflect on what can attack its potential energy.
Why the OPF Does not decay from friction?
Our intuition tells us that whirlwinds are not eternal, that they always break up due to some kind of friction. Friction is different, and one of the reasons that can destroy the OPF, according to people, will be Rossby waves. Rossby waves are one of the types of atmospheric waves that exist because the atmosphere is a rotating spherical shell, and not a rotating plane. They are often found in the atmosphere, and move at low speed. People thought that the OPF would start emitting Rossby waves that would take energy from him. When unexpected events occur in the atmosphere, for example, two vortices collide, then Rossby waves appear. But usually after the formation of a vortex, it finishes emitting Rossby waves, so there is no evidence that the emission of Rossby waves will destroy the OPF in a quasi-equilibrium state.
What else can stop it?
If we start to study the question of what can attack the OPF and destroy it, we will have to think not only of the influence on factors such as friction on kinetic energy; You will have to think about what is more important – that it is attacking potential energy. There is a well-known reason for potential leakages of potential energy – it is called "radiant equilibrium". If I could cool one part of the earth's atmosphere, I could get a stopwatch and say, "So, I wonder what time this area will warm up again and get into a radiant equilibrium with the surrounding atmosphere?" Or, if I did somewhere small I could ask: "How long will it take to establish an equilibrium due to the transfer of photons and everything else, after which my site will lose its temperature differences?" It is known from the calculations of other scientists that in the place of the atmosphere where the OPF is located, Cold or hot Sites disappear in about four and a half years – this time is required to ensure that especially warm or cold areas are completely indistinguishable from the environment. So we made a lot of numerical simulations, and if we introduce a warming or cooling effect into our computer model, it turns out that the OPF dissolves in four and a half years.
What does it feed?
The average speed around this spot is about three hundred kilometers per hour. Jet streams also move at about the same speed. But their vertical speeds are considered very small. They are likely to be of the order of centimeters per hour, and therefore they are usually neglected. But in large areas of the atmosphere vertical winds are constantly appearing, and therefore we think that they can not be written off. We think that to destroy the OPF tries heat, transferred to the cold cover and from the warm bottom, and trying to establish a radiant equilibrium. But we believe that the OPF can survive despite this radiant heat transfer, because its vertical velocity is very small.
It can practically be assumed that when the wind falls, it becomes warmer, and when it rises, it cools. Thermal radiation of photons inside the OPF tries to equalize the temperature of its cap and bottom with the temperature of the surrounding atmosphere. This should make the cold dense lid warmer, and eventually it should disappear, which will destroy the OPF.
But at the beginning of the dispersion of the OPF, the pressure balance is lost. The loss of balance allows high pressure in the center of the OPF to expel gases vertically through a weakened lid. When lifting, the wind cools down, which supplies the cover with new cold air, as a result, it cools and becomes heavier. Approximately the same process takes place at the bottom of the OPF, and it restores a warm bottom, which tries to destroy thermal radiation.
Plus, a vertically upwardly moving gas that passes through the disappearing lid exits the OPF and eventually ceases to rise, and It flattens horizontally in an area many times larger than the OPF area. Then it stops moving outside and goes down. This descending gas pushes the atoms and molecules of the atmosphere surrounding the OPF down, reducing their potential energy. As a result, the gas finishes its journey, returning to the center of the OPF. On the way home, the gas collects potential energy liberated from the atmosphere surrounding the OPF.
Collecting this energy balances the loss of the OPF energy through thermal radiation. In computer simulations, it is possible to measure the direction and power of all energies going in and out of the OPF, and this entire energy budget perfectly converges. There is a large leakage of potential energy into the atmosphere surrounding the OPF because of the gas circulation, but there is nothing wrong with this, since the Sun restores radiant equilibrium in this place and gives additional energy. So in the end it turns out that the Sun serves as the energy source preventing the disappearance of the OPF.
What is the value of studying the atmosphere of a distant planet?
If you do not understand how Jupiter works in our own solar system, how can you understand how Jupiters work around other suns? Now it is very fashionable to look for other Jupiters in other solar systems, since we are wondering if there are other planets, and whether there can be life on them. The study of planets circulating around other suns, you need to start somewhere, you need to make silly mistakes. This is how the scientific field of research develops.
And now – a complaint. NASA is an excellent organization, and I am grateful to her for the funding allocated to me and my fellow theorists. But the amount of money we spend on equipment – in order to send devices into space, in comparison with the amount of money we spend on analyzing data obtained from those same devices, is very unbalanced. Since the Voyagers 31 years ago, huge amounts of data have been received, and they have not yet been processed. To receive financing for their processing is extremely difficult. Usually everyone says: "You need to do something new and interesting, with new data! Do not go back in time and mess with the old data! "But there is also a lot of valuable stuff in there! But Congress only give equipment.
Everybody loves equipment. And what you need is NASA – this is another Carl Sagan. Charles had the talent to persuade people to respect our discoveries themselves, and not just machines that made these discoveries possible.