<blockquote>
  <p>Oxidation states of sulphur vary between -2 and +6. Sulphur compounds are generally
  emitted in reduced form. They are then oxidised in the Earth’s atmosphere, generally to
  SO2
  , a +4 oxidation state. Around 65% (the remainder is removed by dry deposition) of this
  sulphur dioxide is eventually oxidised to the +6 state of H2SO4
  , where SO2 –
  4
  is the sulphate
  ion. Sulphur is stable in the presence of oxygen in this state. The higher-state compounds
  also generally have a greater affinity to water, meaning they are more readily removed from
  the atmosphere by wet deposition. </p>
</blockquote>

<p><a href="http://www.met.reading.ac.uk/~qq002439/aferraro_sulphcycle.pdf" rel="nofollow noreferrer">The natural atmospheric sulphur cycle and its response to anthropogenic perturbations, Angus J. Ferraro</a></p>

CC BY-SA 4.0
2019-08-05T07:50:53.083Z
In simple terms, is sulphur dioxide converted to sulphur trioxide by natural processes, and if so, how long does this take?
Michael Walsby
CC BY-SA 4.0
2019-08-06T11:00:08.110Z
Why give complex and long winded answers when a simple answer is all that's required? Example: YES,THERE IS A NATURAL PROCESS WHICH OXIDISES SO2 TO SO3 BY A REACTION WITH OXYGEN IN THE ATMOSPHERE, THIS PROCESS TAKES X NUMBER OF DAYS,WEEKS,MONTHS.
Michael Walsby
CC BY-SA 4.0
2019-08-06T14:24:20.270Z
@MichaelWalsby Ferraro discusses residence time on p.3 . Days in the troposphere, years in the stratosphere.
Keith McClary
CC BY-SA 4.0
2019-08-06T14:33:24.080Z
Thanks. I wonder how it works on Venus, where there is hardly any oxygen in the atmosphere.
Michael Walsby
CC BY-SA 4.0
2019-08-05T03:23:32.240Z
2019-08-05T03:23:32.240Z
Keith McClary
<p>I often see claims that volcanic emissions of sulphur dioxide, on Earth and on the planet Venus, creates sulphuric acid when it combines with water vapour. It doesn't. Sulphur dioxide creates sulphurous acid, which is less corrosive than sulphuric acid. To make sulphuric acid you need sulphur trioxide. Is there a natural process which converts sulphurous acid into sulphuric acid, or has one  acid been confused with the other? </p>

<atmospheric-chemistry><air-pollution>
Origin of Sulphuric Acid in the Atmosphere
Michael Walsby
# Origin of Sulphuric Acid in the Atmosphere

(Asked by: username_0 on 2019-08-04)

I often see claims that volcanic emissions of sulphur dioxide, on Earth and on the planet Venus, creates sulphuric acid when it combines with water vapour. It doesn't. Sulphur dioxide creates sulphurous acid, which is less corrosive than sulphuric acid. To make sulphuric acid you need sulphur trioxide. Is there a natural process which converts sulphurous acid into sulphuric acid, or has one acid been confused with the other?

**Tags:** atmospheric-chemistry, air-pollution


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## 1 answers

### Answer by username_1 on 2019-08-05. Score: 4

> Oxidation states of sulphur vary between -2 and +6. Sulphur compounds are generally
> emitted in reduced form. They are then oxidised in the Earth’s atmosphere, generally to
> SO2
> , a +4 oxidation state. Around 65% (the remainder is removed by dry deposition) of this
> sulphur dioxide is eventually oxidised to the +6 state of H2SO4
> , where SO2 –
> 4
> is the sulphate
> ion. Sulphur is stable in the presence of oxygen in this state. The higher-state compounds
> also generally have a greater affinity to water, meaning they are more readily removed from
> the atmosphere by wet deposition.

[The natural atmospheric sulphur cycle and its response to anthropogenic perturbations, Angus J. Ferraro](http://www.met.reading.ac.uk/~qq002439/aferraro_sulphcycle.pdf)

> **Comments:**
> **username_0**: In simple terms, is sulphur dioxide converted to sulphur trioxide by natural processes, and if so, how long does this take?  
> **username_0**: Why give complex and long winded answers when a simple answer is all that's required? Example: YES,THERE IS A NATURAL PROCESS WHICH OXIDISES SO2 TO SO3 BY A REACTION WITH OXYGEN IN THE ATMOSPHERE, THIS PROCESS TAKES X NUMBER OF DAYS,WEEKS,MONTHS.  
> **username_1**: @username_0 Ferraro discusses residence time on p.3 . Days in the troposphere, years in the stratosphere.  
> **username_0**: Thanks. I wonder how it works on Venus, where there is hardly any oxygen in the atmosphere.  

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