This time we will deal with the atmosphere and the phenomena that characterize it. Second article in the series
atmosphere
The photographs of the atmosphere at different wavelengths reveal additional faces of Saturn. At a wavelength of 2.3 microns, the day side of Saturn is greenish-yellow. At 5.1 microns, the light reflection from Saturn is weak and the dominant factor in the light coming from the star is the heat radiation emitted from it. The emission of heat is dominant on the dark side to the same extent that the phenomenon exists in the North Pole and in the areas shadowed by rings A and B. Variable amounts of clouds in the upper atmosphere block the heat radiation and create spots that are in motion due to the strong winds. The photograph has a wavelength of 5.1 microns. The light comes from below at night and is formed inside Saturn, rises up and escapes into space. Deep clouds block this light. In this place you see dark lines and spots surrounding Saturn. It is worth noting that at this wavelength you can see the deep clouds during some hours of the day, especially in places where the haze layer is thin and the sun's glare on them is minimal. These clouds are probably made of ammonium hydrosulfide. And it is impossible to see them in the light reflected on the side of the day (7).
A combination of terrestrial observations that lasted 22 years and the findings of the Cassini revealed a wavy phenomenon that the Earth can see once every 15 years. This pattern is similar to the phenomenon that occurs in the upper layers of the Earth's atmosphere. On Earth, this oscillation lasts for two years. A similar phenomenon also occurs on Jupiter and lasts for four years. It creates waves that move back and forth in the upper atmosphere of Saturn. In this space the temperatures move from one height to another in the shape of candy canes. Sometimes they are hot and sometimes they are cold. The changing temperatures cause the winds in this area to change direction from east to west, to jump back and forth. The result is that the entire area sways like a wave. The heat changes revealed other phenomena. One of them is heat and cold transitions at the equator and heat and cold exchanges on both sides of the equator every half year of Saturn (4).
At high latitudes in the Southern Hemisphere there are bright bands associated with changing directions from east to west and west to east of the jet streams. These jet streams create swirling boundary lines under the influence of shear winds and density differences between adjacent bands (9). In photo 06503 PIA at high southern latitudes the atmosphere contains hydrogen and helium Pure and little of the stratospheric haze that causes darkening near the pole(10).
clouds
Between the years 1994-2002, the Hubble telescope transmitted to Israel over 100 high-resolution photographs of Saturn and diagnosed more than 100 cloud characteristics that enabled the measurement of winds. In terms of seasons, the southern hemisphere was in the spring and early summer season. During this period there were changes in the equatorial clouds. The formations observed by the Voyager spacecraft were bright plumes. The Hubble telescope observed more complex plume formations(11). In general, the clouds and haze in the Northern Hemisphere are thinner than those in the Southern Hemisphere, probably due to seasonal changes. Areas with a light red color indicate that they are relatively free of deep clouds and particles, while a dark red color indicates cloudy areas. Photographs of this type show deep clouds on both the day and night sides of Saturn(6).
In photo 03557 PIA you see clouds at a depth of 30 km below the clouds that are usually seen in the atmosphere. This photo is different from the view of Saturn scattering sunlight (12). In photo 09186 PIA you can see clouds at different depths. The red color in the photo shows radiation with a wavelength of 5 A micron or heat generated in the interior of Saturn escapes. Clouds at a depth of 100 km block the light and you can see them in shading against the background of Saturn's internal fiery heat(13). A photograph combining visible and infrared light from 27.4.2006/40/60,000 revealed a new phenomenon at latitude N°3.5. A configuration of strings of pearls was discovered that extends along 14 and at an interval of XNUMX ° from one another. The order in which they appear raises the possibility that this is the exposure of a large planetary wave(XNUMX).
A series of photographs taken at the South Pole by two research instruments revealed a swirling hurricane-like storm in this area and clouds at different depths around the pole. The different wavelengths at which the photographs were taken indicate the depth of the clouds that extend to a height of tens of kilometers. Hundreds of storms surround the pole and they appear as black spots in infrared and the bright and black spots in sunlight. Each spot represents a storm. It is nothing like what is observed on other planets. The effectiveness of these cloud storms in hiding Saturn's internal heat shows how thick they are(15).
Lightnings and thunders
The researchers noticed a small lightning storm during 2005 that is fundamentally different from what is known on Earth. Monitoring of a storm of electrical breakdowns began on January 23.1.2006, 1000, the largest of the US territory and in which lightning flashes are 1 times stronger than those existing on Earth. The storm is probably a source of radio wave emission, a product of electrical breakdowns deep within the atmosphere. The lightning can appear suddenly and last for several weeks or even a month. The source of this meteorological phenomenon is unclear, although it may be related to the internal heat of Saturn. The intensity of the lightning is greater than that observed by Voyager 2004. The place where the radio waves observed by the Cassini in 3500 during its approach to Saturn were emitted was named "Storm Alley" due to the high activity observed there. The length of the storm in the north-south direction is 16 km (168). The exact location of the storm is W° 36 S° XNUMX.
The electrical storms are similar to earthly thunder but on a larger scale. The diameter of Saturn's storms is thousands of kilometers and the strength of radio signals is stronger than the strongest storms on Earth. Flashes of light in the ongoing storms create the radio waves called electrostatic discharges of Saturn. One of these storms was observed starting on November 27.11.2007, 17 and lasted for several months. The storm was observed in the area called the storm avenue (XNUMX).
storms
It turned out that Saturn is a very dynamic planet. In its atmosphere there are many powerful storms and strong winds blow in it. In the Southern Hemisphere, a lot of activity was noticed in particular. To illustrate the scope of the activity of the spirits, several examples will be presented according to chronological order in terms of the dates of their occurrence.
1. 10.8.2004 - Several dark storms were photographed, including a storm with a bright ring around it (18).
2. 18.9.2004 - A bright storm on Saara Avenue (19).
3. 19.9.2004 - many storms were photographed and around them bright clouds in a latitude where the winds blow towards the west. One of the only places where the winds blow in this direction. The place is the storm avenue (20).
4. 6.7.2005 - Formations like thin threads move in a linear motion around two elliptical storms that move in the opposite direction to the movement of the hurricanes surrounding Saturn. It is not clear what the origin of these threads is. It is possible that they are
represent material connecting storms that split from one big storm. It could also be that the spirals are winds moving in the atmosphere (21).
5. 27.1.2006 - A rare and powerful storm was observed on the night side of Saturn. It is possible that the storm is a source of radio wave emission coming from electrical breakdowns deep in the atmosphere. The length of the storm in the north-south direction is 3500 km and its location is W °168 S ° 36. This photo was taken When emissions of radio waves were discovered. The emission of radio waves stopped for half a day of Saturn when the storm was on the other side. A narrow strip of cloud crosses the storm from left to right (22).
6. 16.2.2006 - A large lightning was observed in the storm avenue. On the left side from the west (left in the picture) you see a vortex in which the storm moves east relative to the winds moving west at this latitude. Since the Cassini began its observations in this region, two large and powerful storms have developed (23).
7. 19.5.2008 - a series of dark storms are seen in the storm avenue. Each one hundreds of kilometers in diameter (24).
On Earth, in the center of the lower base of hurricanes, the atmospheric pressure is low and high at the top, where the storm is flattened. Storms on Saturn are similar to terrestrial hurricanes, if what you see is indeed tops of clouds. The frequency of storms on Saturn is similar to the frequency of terrestrial storms and the relative part of Saturn's surface that is covered by A cloud cover is similar to that part of the face of the earth that is covered by clouds. For comparison, the diameter of Hurricane Katrina is 380 km, while two storms observed by the Cassini in February 2002 were more than 1000 km in diameter each. The sources of terrestrial hurricanes are the oceans. They provide a large amount of solar energy and at the same time are a source of moisture for convection currents that sweep energy from the oceans into the atmosphere and create cloud storms followed by rain. The mechanism in Saturn is completely different. The inside of Saturn acts like an ocean and it stores energy, but it does not come from the sun. The planet creates its own energy. Storms can merge and split alternately. The logic says that the merging of two storms will give a bigger storm, but the size does not change ( 25).
eddies
A significant part of Saturn's turbulent dynamics is reflected in the giant eddies that take place in the atmosphere. Eddy currents are believed to be created by shear forces acting between westward and eastward jet streams that pass each other in the atmosphere. These phenomena can last for months or years. They can grow by merging with each other until they are sheared off by strong winds. Some of them will be mentioned here in chronological order.
1. 9.10.2004 - A turbulent boundary line between two transverse bands is visible from the repeating rolling of the atmosphere. This is an example of the Kelvin Helmoltz instability that occurs when two liquids of different densities pass by each other at different speeds. This phenomenon is common in the gaseous planets (26).
2. 5.12.2004 - a sort of passing cough while touching each other. The eddy formations at the bottom of the image raise the possibility of eddy interaction between lateral regions of different densities moving at different speeds. A storm with a linear configuration above in the picture indicates more stable conditions in the flow(27).
3. 6.12.2004 - a large elliptical configuration in the southern hemisphere that resembles the great spot of Jupiter, although it is smaller (28).
4. 6.12.2004 - In the lower part of the picture you can see surges that form in the eddy boundary lines between two air masses with different densities moving at different speeds. This movement is in contrast to a darker strip to the north, which has a linear configuration and moves in a stable area without any eddy phenomenon interfering with it. A more northern configuration has a similar morphology(29).
5. 4-5.7.2005 - two photographs with a difference of two Saturn days from each other in the area between S ° 42 - S ° 23. Two vortices intervene between turbulent movements in the atmosphere. In the area below the center of the image at S ° 35 a storm is visible Active that has been observed since the arrival of the Cassini. The observations of the Cassini between February and October 2004 show that most of the elliptical storms near the latitude S °35 move counterclockwise together with small storms that merge with larger storms(30).
6. 20.8.2005 - two photographs taken 23 minutes apart and in which you can see many active eddies in the atmosphere. You can see the stringy structure of the current in the atmosphere. On many of the narrow clouds there are narrow and widening bands that continue and roll over great distances, maintaining their uniqueness and not mixing with air particles nearby. This type of behavior is called two dimensional turbulence. In two-dimensional vorticity, the behavior is that of a flowing liquid, similar to what you see in soap bubbles or a fatty membrane flowing over water. These systems have a large relative thickness and their physics is different from that of three-dimensional vortices(31).
Spirits
On Saturn, very strong winds blow, their speeds vary from place to place and also change over time. For example, when the Voyager spacecraft reached Saturn in 1980-1981, a speed of 1700 km/h was measured, and during the next 20 years it decreased to 1000 km/h (11). A technique used to measure the dynamics of astronomical phenomena is the use of sequences of photographs. It turned out that the winds around the South Pole blow clockwise and their speed is 550 km/h (32). Just like on Earth, so also on Saturn there are jet streams. Such a stream was detected in a photo taken on February 5.2.2005, 27.5 at S °320 and winds blowing quickly were observed in it of 10 km/h. Continuous monitoring of clouds in this area for 33 hours (as Saturn's moon) showed that the eddies on each side of the jet stream transfer energy and momentum to it so that the winds tend to blow in this stream. The winds are so strong that they merge with each other and pull the eddies into lines bright flow. The analysis of the photographs covering most of the southern hemisphere raises the possibility that similar processes occur on the entire planet and explain the long-term stability - tens of years - of the changing patterns to the east and west of the jet streams. This is what also happens on Jupiter and on Earth along the eastern coastline of the USA The eddies in this photograph create circulations of up and down movements at different latitudes that can explain the banded structure of the global cloud array in Jupiter-like planets(17.9.2007). In the photo from September 360, 34, a wind was measured at a speed of XNUMX km/h (XNUMX).
Sources:
7. PIA09212: Neon Saturn
http://photojournal.jpl.nasa.gov/catalog/PIA09212
8."Saturn does the wave in upper atmosphere" 7.5.2008
http://www.spaceflightnow.com/news/n805/07saturn/
9.PIA06546: Nope not Jupiter
http://photojournal.jpl.nasa.gov/catalog/PIA06546
10.PIA06503: South pole in ultraviolet
http://photojournal.jpl.nasa.gov/catalog/PIA06543
11. Whitehouse D.-"Saturn's winds decrease" 5.6.2003
http://news.bbc.co.uk/2/hi/science/nature/1962688.stm
12.PIA03557: A new view of Saturn
http://photojournal.jpl.nasa.gov/catalog/PIA03557
13.PIA09186: Saturn's strange hexagon
http://photojournal.jpl.nasa.gov/catalog/PIA09186
14.PIA01941: String of pearls
http://photojournal.jpl.nasa.gov/catalog/ PIA01941
15.PIA08333: Saturn's surprisingly stormy south
http://photojournal.jpl.nasa.gov/catalog/ PIA08333
16. "Cassini sees giant lighting storm on Saturn" 14.2.2006 http://www.sciencedaily.com/releases/2006/02/060215090726.htm
17. "NASA spacecraft tracks raging Saturn storm" 30.4.2008
http://www.saturndaily.com/reports/ NASA _Spacecraft _Tracks _Raging_ Saturn _Storm_999.html
18.PIA06482: The stormy south
http://photojournal.jpl.nasa.gov/catalog/PIA06482
19.PIA06517: The storms continue
http://photojournal.jpl.nasa.gov/catalog/PIA06517
20.PIA06507: Energetic atmosphere
http://photojournal.jpl.nasa.gov/catalog/PIA06507
21.PIA07564: Filaments and vortices
http://photojournal.jpl.nasa.gov/catalog/PIA07564
22.PIA07789: Storm at night (reprojected view)
http://photojournal.jpl.nasa.gov/catalog/PIA07789
23.PIA08142: Against the current
http://photojournal.jpl.nasa.gov/catalog/PIA08142
24.PIA10411:Swirling storms
http://photojournal.jpl.nasa.gov/catalog/PIA10411
25. "Saturn storms dwarf Earth hurricanes in size and longevity" 20/4/2006
http://www.saturndaily.com/reports/ Saturn _Storms _Dwarf_ Earth _Hurricanes_Iin_ Size_ And_ longevity.html
26.PIA06502:Rough around the edges
http://photojournal.jpl.nasa.gov/catalog/PIA06502
27.PIA06576: Going with the flow
http://photojournal.jpl.nasa.gov/catalog/PIA06576
28.PIA06546:Nope'not Jupiter
http://photojournal.jpl.nasa.gov/catalog/PIA06546
29:PIA06580:Mixing Saturn
http://photojournal.jpl.nasa.gov/catalog/PIA06580
30.PIA07562 :Saturn's anti-hurricanes
http://photojournal.jpl.nasa.gov/catalog/PIA07562
31.PIA07594: "2-D" flow
http://photojournal.jpl.nasa.gov/catalog/PIA07594
32."NASA sees into the eye of a monster storm on Saturn" 10.11.2006
http://www.saturndaily.com/reports/ NASA _Sees _Into _The_ Eye Of_ A_ Monster_ Storm_ On_ Saturn_999.html
33.PIA08368 : Powering Saturn's jets
http://photojournal.jpl.nasa.gov/catalog/PIA08368
34.PIA09755 : Whirlwinds of Saturn
http://photojournal.jpl.nasa.gov/catalog/PIA09755
