Scientist explains sulfur behavior in Venus atmosphere

April 26, 2016

The beautiful dark stripes on ultraviolet images of Venus's disc are in no way connected with the crystalline sulfur particles in its atmosphere - the ultraviolet is absorbed by another substance. This has been proven by data obtained from the first ever model of the distribution of sulfur in Venus's gaseous envelope which has been developed by the head of MIPT's Laboratory of High Resolution Infrared Spectroscopy of Planetary Atmospheres, Prof. Vladimir Krasnopolsky.

The results of the study have been published in the scientific journal Icarus.

If we look at Venus in a normal optical telescope, we see only a dull yellowish-white sphere without any other distinguishing features. However, if we capture an image in the ultraviolet range, the picture changes drastically - dark and light areas appear on the disc, reflecting the dynamics of the atmosphere.

"These areas mean that somewhere in the upper cloud layer there is a substance that is absorbing UV radiation. Over the past 30 years there have been a wide range of hypotheses as to what this substance could be. Many scientists believed that sulfur particles were responsible for the absorption. But now we will have to abandon this hypothesis," says Krasnopolsky.

He already questioned the "sulfur hypothesis" in 1986 by demonstrating that the amount of the aerosol was not enough to explain the effect of UV absorption. In the new paper, Krasnopolsky presents the first photochemical model of the formation of sulfur particles in Venus's clouds. In particular, the model included certain processes of the breakdown of sulfur compounds under the influence of light that had not been studied in previous models. As a result, a profile was compiled of the concentration of sulfur aerosol at various altitudes.

The model showed that sulfur aerosol is predominantly found in the lower cloud layer. Its mass constitutes approximately one tenth of the layer and it is not externally visible. However, observations in the near UV radiation range obtained from the Soviet interplanetary station Venera 14 indicate that absorption in this range occurs in the upper cloud layer at the altitude of approximately 60 km.

"This means that sulfur aerosol cannot be the cause of absorption of Venus's atmosphere in the near UV range," concludes Krasnopolsky.

In his opinion, the main absorber and "artist" drawing the stripes on Venus's disc could be ferric chloride (FeCl3), which was discovered in the planet's atmosphere by the X-ray fluorescence spectrometer on board Venera 12.

The cloud layer of Venus is mainly composed of liquid droplets of sulfuric acid (H2SO4). In 1981, the Space Research Institute of the RAS conducted laboratory tests of the reflection coefficient in the near UV range for a 1% solution of ferric chloride in sulfuric acid, and their results are fully consistent with the observations of the present study.

"We can therefore consider this mixture of sulfuric acid and ferric chloride to be the most likely substance causing this very mysterious UV absorption," says Krasnopolsky.
-end-


Moscow Institute of Physics and Technology

Related Atmosphere Articles from Brightsurf:

ALMA shows volcanic impact on Io's atmosphere
New radio images from ALMA show for the first time the direct effect of volcanic activity on the atmosphere of Jupiter's moon Io.

New study detects ringing of the global atmosphere
A ringing bell vibrates simultaneously at a low-pitched fundamental tone and at many higher-pitched overtones, producing a pleasant musical sound. A recent study, just published in the Journal of the Atmospheric Sciences by scientists at Kyoto University and the University of Hawai'i at Mānoa, shows that the Earth's entire atmosphere vibrates in an analogous manner, in a striking confirmation of theories developed by physicists over the last two centuries.

Estuaries are warming at twice the rate of oceans and atmosphere
A 12-year study of 166 estuaries in south-east Australia shows that the waters of lakes, creeks, rivers and lagoons increased 2.16 degrees in temperature and increased acidity.

What makes Saturn's atmosphere so hot
New analysis of data from NASA's Cassini spacecraft found that electric currents, triggered by interactions between solar winds and charged particles from Saturn's moons, spark the auroras and heat the planet's upper atmosphere.

Galactic cosmic rays affect Titan's atmosphere
Planetary scientists using the Atacama Large Millimeter/submillimeter Array (ALMA) revealed the secrets of the atmosphere of Titan, the largest moon of Saturn.

Physics: An ultrafast glimpse of the photochemistry of the atmosphere
Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

Using lasers to visualize molecular mysteries in our atmosphere
Molecular interactions between gases and liquids underpin much of our lives, but difficulties in measuring gas-liquid collisions have so far prevented the fundamental exploration of these processes.

The atmosphere of a new ultra hot Jupiter is analyzed
The combination of observations made with the CARMENES spectrograph on the 3.5m telescope at Calar Alto Observatory (Almería), and the HARPS-N spectrograph on the National Galileo Telescope (TNG) at the Roque de los Muchachos Observatory (Garafía, La Palma) has enabled a team from the Instituto de Astrofísica de Canarias (IAC) and from the University of La Laguna (ULL) to reveal new details about this extrasolar planet, which has a surface temperature of around 2000 K.

An exoplanet loses its atmosphere in the form of a tail
A new study, led by scientists from the Instituto de Astrofísica de Canarias (IAC), reveals that the giant exoplanet WASP-69b carries a comet-like tail made up of helium particles escaping from its gravitational field propelled by the ultraviolet radiation of its star.

Iron and titanium in the atmosphere of an exoplanet
Exoplanets can orbit close to their host star. When the host star is much hotter than our sun, then the exoplanet becomes as hot as a star.

Read More: Atmosphere News and Atmosphere Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.