The article was kept by DrKay via FACBot ( talk) 8:19, 26 June 2016 (UTC) [1].
The article has undergone major change since the latest FAR in 2008 (e.g. [2]). It no longer looks like the same article. There are a few issues that pop out to me - there is an over-use of images and not always in the correct context (one example "Pioneer Venus Multiprobe"). Some sections are very brief and refer to secondary articles without a summary that reads well and fits in well on the Venus page itself. The intro is a little brief and could be better written. Anon 09:28, 8 January 2016 (UTC) reply
Above spelling issues resolved. Serendi pod ous 10:36, 14 January 2016 (UTC) reply
Graeme Bartlett ( talk) 11:29, 20 January 2016 (UTC) reply
Keep: I believe this article now meets FA Criteria User:Dunkleosteus77 | push to talk 23:23, 7 April 2016 (UTC) reply
@ Sir Anon, Graeme Bartlett, and Dunkleosteus77: Have your concerns been addressed here? @ Serendipodous: any response to Nergaal's question? Nikkimaria ( talk) 17:51, 2 April 2016 (UTC) reply
"The clouds are approximately bounded by the evaporation temperature of H2SO4 below and the top of the convectively mixed troposphere above. Their composition is primarily liquid droplets of concentrated sulfuric acid, with an additional ultraviolet (UV) absorber in the upper layers and large, possibly solid, particles near the base level, both of unknown composition."
"Sulfur Dioxide
The high sulfur content of the atmosphere, including the H2SO4 clouds, is a powerful indicator of recent volcanic activity, since gases like sulfur dioxide have a short lifetime in the atmosphere before they are removed by interaction with the surface. The measured abundance of SO2 in the deep atmosphere is about 180ppm, which is more than 100 times too high to be at equilibrium with the surface. The time constant for the decline of the sulfur abundance in the atmosphere if the source were removed is a few million years, indicating that the atmospheric sulfur must be of recent origin. Pioneer Venus UV spectra showed a decline by more than a factor of 10 in sulfur dioxide abundance at the cloud tops over a 5-year period, and more recently, Venus Express has also detected very large, long- and short-term variations in SO2 at all altitudes from the clouds to the thermosphere.
The high level of SO2 in the atmosphere is the source for the concentrated sulfuric acid that is the dominant component of the clouds (see Section 4.4 below). Although less well understood, it is probably the nonuniform distribution of SO2 and the formation of trace amounts of elemental sulfur and possibly other sulfur compounds that gives rise to the UV markings in the clouds that the visible face of Venus. Apart from forming the highly reflective clouds that tend to cool the planet, sulfur dioxide is a greenhouse gas contributing to the warming of the surface (Section 6)."
"Cloud Chemistry
The high abundance of sulfur dioxide in the atmosphere leads to the formation of the concentrated sulfuric acid cloud layers via a chemical system involving the photolytic destruction of carbon dioxide by solar UV radiation, summarized by
CO2→CO+O
followed by reactions equivalent to
SO2+H2O+O=H2SO4.
This sequence forms the acid near the visible cloud tops, where it combines with other H2O molecules to produce the hydrated acid droplets that are the main constituent of the clouds. The degree of hydration varies between perhaps 10% and 25%, with 20% (4H2SO4.H2O) typical.
A cloud particle of the observed mean radius (∼1μm) has a sedimentation velocity of 7.5m/day at 60km; this velocity varies as the square of the size. Although small, these velocities, aided by coagulation, eventually carry the particles out of the cloud to lower altitudes and higher temperatures, where they will evaporate and, at still lower heights, decompose back into water and sulfur dioxide. Atmospheric mixing carries these gases back upward where they can again contribute to the formation of H2SO4. An important intermediate is the reactive free radical SO, and probably some elemental sulfur is produced. UV spectra (pertaining to the region above the clouds) reveal the presence of small amounts of SO2 shown in Table 14.1, but much less than the amounts that have been measured below the clouds.
Sulfuric acid is perfectly colorless in the blue and near-UV regions, and the yellow coloration that provides the contrasts of Figure 14.1 must be caused by something else. The most likely thing is elemental sulfur, but yellow compounds are abundant in nature, and the identification remains tentative. The photochemical models do predict production of some sulfur, but it is a minor by-product, and the amount produced is uncertain. It is also unclear what constitutes the large Mode 3 particles in the lower cloud. Optical data suggests solid, irregular particles coated with sulfuric acid; the most likely candidate for the solid material is volcanic ash."
I'm too busy with exams to process this all into the article right now, but I think it has the information we need to resolve the issue. I'll be back in a couple weeks to do it if no one has by then. Hope this helps! A2soup ( talk) 23:02, 29 April 2016 (UTC) reply
The article was kept by DrKay via FACBot ( talk) 8:19, 26 June 2016 (UTC) [1].
The article has undergone major change since the latest FAR in 2008 (e.g. [2]). It no longer looks like the same article. There are a few issues that pop out to me - there is an over-use of images and not always in the correct context (one example "Pioneer Venus Multiprobe"). Some sections are very brief and refer to secondary articles without a summary that reads well and fits in well on the Venus page itself. The intro is a little brief and could be better written. Anon 09:28, 8 January 2016 (UTC) reply
Above spelling issues resolved. Serendi pod ous 10:36, 14 January 2016 (UTC) reply
Graeme Bartlett ( talk) 11:29, 20 January 2016 (UTC) reply
Keep: I believe this article now meets FA Criteria User:Dunkleosteus77 | push to talk 23:23, 7 April 2016 (UTC) reply
@ Sir Anon, Graeme Bartlett, and Dunkleosteus77: Have your concerns been addressed here? @ Serendipodous: any response to Nergaal's question? Nikkimaria ( talk) 17:51, 2 April 2016 (UTC) reply
"The clouds are approximately bounded by the evaporation temperature of H2SO4 below and the top of the convectively mixed troposphere above. Their composition is primarily liquid droplets of concentrated sulfuric acid, with an additional ultraviolet (UV) absorber in the upper layers and large, possibly solid, particles near the base level, both of unknown composition."
"Sulfur Dioxide
The high sulfur content of the atmosphere, including the H2SO4 clouds, is a powerful indicator of recent volcanic activity, since gases like sulfur dioxide have a short lifetime in the atmosphere before they are removed by interaction with the surface. The measured abundance of SO2 in the deep atmosphere is about 180ppm, which is more than 100 times too high to be at equilibrium with the surface. The time constant for the decline of the sulfur abundance in the atmosphere if the source were removed is a few million years, indicating that the atmospheric sulfur must be of recent origin. Pioneer Venus UV spectra showed a decline by more than a factor of 10 in sulfur dioxide abundance at the cloud tops over a 5-year period, and more recently, Venus Express has also detected very large, long- and short-term variations in SO2 at all altitudes from the clouds to the thermosphere.
The high level of SO2 in the atmosphere is the source for the concentrated sulfuric acid that is the dominant component of the clouds (see Section 4.4 below). Although less well understood, it is probably the nonuniform distribution of SO2 and the formation of trace amounts of elemental sulfur and possibly other sulfur compounds that gives rise to the UV markings in the clouds that the visible face of Venus. Apart from forming the highly reflective clouds that tend to cool the planet, sulfur dioxide is a greenhouse gas contributing to the warming of the surface (Section 6)."
"Cloud Chemistry
The high abundance of sulfur dioxide in the atmosphere leads to the formation of the concentrated sulfuric acid cloud layers via a chemical system involving the photolytic destruction of carbon dioxide by solar UV radiation, summarized by
CO2→CO+O
followed by reactions equivalent to
SO2+H2O+O=H2SO4.
This sequence forms the acid near the visible cloud tops, where it combines with other H2O molecules to produce the hydrated acid droplets that are the main constituent of the clouds. The degree of hydration varies between perhaps 10% and 25%, with 20% (4H2SO4.H2O) typical.
A cloud particle of the observed mean radius (∼1μm) has a sedimentation velocity of 7.5m/day at 60km; this velocity varies as the square of the size. Although small, these velocities, aided by coagulation, eventually carry the particles out of the cloud to lower altitudes and higher temperatures, where they will evaporate and, at still lower heights, decompose back into water and sulfur dioxide. Atmospheric mixing carries these gases back upward where they can again contribute to the formation of H2SO4. An important intermediate is the reactive free radical SO, and probably some elemental sulfur is produced. UV spectra (pertaining to the region above the clouds) reveal the presence of small amounts of SO2 shown in Table 14.1, but much less than the amounts that have been measured below the clouds.
Sulfuric acid is perfectly colorless in the blue and near-UV regions, and the yellow coloration that provides the contrasts of Figure 14.1 must be caused by something else. The most likely thing is elemental sulfur, but yellow compounds are abundant in nature, and the identification remains tentative. The photochemical models do predict production of some sulfur, but it is a minor by-product, and the amount produced is uncertain. It is also unclear what constitutes the large Mode 3 particles in the lower cloud. Optical data suggests solid, irregular particles coated with sulfuric acid; the most likely candidate for the solid material is volcanic ash."
I'm too busy with exams to process this all into the article right now, but I think it has the information we need to resolve the issue. I'll be back in a couple weeks to do it if no one has by then. Hope this helps! A2soup ( talk) 23:02, 29 April 2016 (UTC) reply