<p>According to Wikipedia, <a href="https://en.wikipedia.org/wiki/Haze" rel="nofollow noreferrer"><strong>haze</strong></a> is an atmospheric phenomenon in which dry particulates obscure the clarity of the sky.</p>

<p>Whereas haze is thought of as a phenomenon of dry air, mist formation is a phenomenon of humid air.</p>

<p>However, haze particles may act as condensation nuclei for the subsequent formation of mist droplets; such forms of haze are known as "wet haze".</p>

<p>In meteorological literature, the word haze is generally used to denote visibility-reducing aerosols of the <strong>wet</strong> type.</p>

<p>According to Wikipedia, <a href="https://en.wikipedia.org/wiki/Cloud" rel="nofollow noreferrer"> <strong>a cloud</strong></a> is an aerosol with a <strong>visible</strong> mass of liquid droplets, frozen crystals or particals suspended in the atmosphere, and the droplets <strong>don't have to be made of water.</strong></p>

<p><a href="http://www.hou.usra.edu/meetings/venus2014/pdf/6005.pdf" rel="nofollow noreferrer">This article</a> states that standard cloud models for Venus consider that all clouds and hazes are composed of liquid droplets of sulfuric acid mixed with water, with sulfuric acid making accounting for 75% to 96% by weight of the cloud composition.
However, other minor constituents may make up the cloud particles.</p>

<p><strong>Clearly regarding the mixture of water and sulfuric acid there is no distinction between clouds and hazes on Venus.</strong></p>

<p>In <a href="https://www.lpi.usra.edu/vexag/meetings/archive/vexag_4th/nov_2007/presentations/toon.pdf" rel="nofollow noreferrer">another article</a> it can be seen on images that the altitude from 30-48 km of the atmosphere of Venus is named "the thin haze region ", whereas
the altitude from 48-50 km is called "lower cloud region ". </p>

<p>The figure on page 14 of <a href="https://www.mps.mpg.de/phd/theses/venus-cloud-structure-and-radiative-energy-balance-of-the-mesosphere.pdf" rel="nofollow noreferrer">the dissertation of Yeon Joo Lee</a> also shows that below the cloud layers there is this "thin haze region" which has almost a thousandfold less <a href="https://en.wikipedia.org/wiki/Extinction_coefficient" rel="nofollow noreferrer">extinction coëfficiënt</a> than the clouds above it.</p>

<p><strong>Apparently this huge difference in absorbing the light explains the difference and appearance between sulfuric clouds and sulfuric haze on Venus.</strong></p>

<p>Figure 4 of Bullock and Grinspoon 2001 (paywalled) <a href="https://www.sciencedirect.com/science/article/pii/S0019103500965709" rel="nofollow noreferrer">The Recent Evolution of Climate on Venus</a> (Icarus 150, 1, Mar. 2001, pp 19-37) shows the abundances of H<span class="math-container">$_2$</span>SO<span class="math-container">$_4$</span> and H<span class="math-container">$_2$</span>O in the cloud region of the atmosphere of Venus. A non-paywalled version can be found with an internet search, but since it does not use https I won't include the link explicitly here.</p>

<p><a href="https://i.sstatic.net/wqRfx.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/wqRfx.png" alt="Fig 4 Bullock &amp; Grinspoon 2001 Venus aerosols"></a></p>

<p>Explicitely it shows H<span class="math-container">$_2$</span>SO<span class="math-container">$_4$</span> as a gas in the thin haze region and only in the cloud region there is a mixture of water and sulfuric acid liquid.</p>

CC BY-SA 4.0
2018-05-12T19:37:03.440Z
Thanks for your answer! When you say "According to Wikipedia" it would be a really good idea to add a link directly to the section where it says it, and also add a block quote in case the link breaks. We can't just "read Wikipedia to the OP" in an answer in Stack Exchange.
uhoh
CC BY-SA 4.0
2018-05-13T09:14:51.313Z
@ Why a link if i already gave the necessary information ? It's not that much effort to look for haze and wiki on internet .More important to me, do you agree with my answer, and is maybe a further distinction that clouds have a shape and hazes don't ?
Cornelis
CC BY-SA 4.0
2018-05-13T09:17:53.543Z
That's just good practice throughout most science and fact-based SE sites. One reason, though there are others, is that it helps people know you are not making stuff up (which you are of course not in this case). Adding links to sources of quoted and cited information is almost standard, you can look through other answers and see it's almost universal.
uhoh
CC BY-SA 4.0
2018-05-13T09:28:32.253Z
Wikipedia is really, *really,* **really** big! You might have read this in an article about meteorology, or one about clouds, or one about pollution, or one about haze, or one about sulfuric haze, or one about Venus, or one about atmosphere of Venus... "According to Wikipedia" by itself is not really helpful because it's impossible to check.
uhoh
CC BY-SA 4.0
2018-05-13T10:18:31.833Z
Haze is a distinct article on Wikipedia, it's just logical to look for that !
Cornelis
CC BY-SA 4.0
2018-05-13T10:24:11.257Z
Okay, I'll stop recommending how to write good Stack Exchange answers.
uhoh
CC BY-SA 4.0
2018-05-13T11:52:02.020Z
I appreciate your recommending, but i just wanted to explain my point of view. So since it's just good practice, i think you are allowed to edit my answer. It's good to have exchange of thoughts on this site !
Cornelis
CC BY-SA 4.0
2018-05-26T14:20:16.473Z
@uhoh  I'm sorry if i offended you, i can be rather unwilling sometimes. So i've added a link on my answer. And please, don't stop recommending how to write good Stack Exchange answers, we might learn from them !
Cornelis
CC BY-SA 4.0
2018-05-26T14:29:10.277Z
Oh don't worry about it! In SE it's sometimes difficult to judge when someone is being helpful or just giving a hard time. When I first started I got "beat up" by some people who treat SE as a contact sport rather than the intellectual Smörgåsbord that it is, or at least can be, so it took a while to learn to be defensive, and then longer to un-learn it.
uhoh
CC BY-SA 4.0
2018-06-01T10:16:40.363Z
@uhoh  I came upon an article that gave me more insight in the atmosphere of Venus so i've changed the conclusion in my answer
Cornelis
CC BY-SA 4.0
2018-06-01T12:26:20.963Z
It looks great! This is a really well-researched, reasoned, and explained answer.
uhoh
CC BY-SA 4.0
2018-06-01T12:31:33.643Z
I adjusted the wording of the reference and added the plot, I hope you don't mind. This way if, or *when* the link eventually rots, the answer is still useful.
uhoh
CC BY-SA 4.0
2018-06-01T13:18:02.590Z
Thank you for editing, it certainly looks greater now. Much is still unknown, like the possible condensation nuclei.
Cornelis
CC BY-SA 4.0
2018-06-01T15:25:51.590Z
@uhoh  I've used your "Fig. 4 " to embellish my answer on[ this question] (http://space.stackexchange.com/questions/27467/is-really-almost-all-the-water-in-the-atmosphere-of-venus-above-the-clouds)
Cornelis
CC BY-SA 4.0
2018-06-02T07:57:30.997Z
@uhoh  How can H2SO4 ,b.p. 337 C, be a gas at 45 km, 110 C and 2 atm. ?  Is the link already rotting ?
Cornelis
CC BY-SA 4.0
2018-06-02T12:05:40.683Z
Why don't you ask that as a new question? Include the link and quote the passage as a block quote (use the `>` symbol) you have a choice of SE sites. There is Chemistry SE, but they are a little tougher on new users so if you decide to write it there, be thorough in your question.
uhoh
CC BY-SA 4.0
2018-06-02T12:47:22.590Z
Let us [continue this discussion in chat](https://chat.stackexchange.com/rooms/78347/discussion-between-conelisinspace-and-uhoh).
Cornelis
CC BY-SA 4.0
2018-10-11T08:37:17.557Z
H2SO4 can be a gas beneath the lower cloud boundary because  the partial pressure of it with 3 ppm is of course magnitudes lower than the 2 atm. of the surrounding CO2. I've changed the answer to that extent that the extinction coëfficiënt explains the difference between clouds and haze better  than mass loading does.
Cornelis
CC BY-SA 4.0
2018-05-12T17:18:40.363Z
2018-10-11T08:22:23.030Z
2018-10-11T08:22:23.030Z
Cornelis
<p>In a conversation in comments below <a href="https://space.stackexchange.com/a/27199/12102">this answer</a> to the question in Space Exploration <a href="https://space.stackexchange.com/q/27193/12102">Could we see the surface of Venus after the explosion of a H-bomb in its atmosphere?</a> we're speculating about what terms like sulfuric clouds and sulfuric haze mean, and in particular if they are both made of aerosols based on water.</p>

<p>What might be the difference between sulfuric clouds and sulfuric haze, and do both still require water in the form of an aerosol?</p>

<p><a href="https://i.sstatic.net/nbWK2.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/nbWK2.png" alt="enter image description here"></a></p>

CC BY-SA 4.0
2018-05-12T16:09:59.583Z
This may be of use: https://www.space.com/5011-mysterious-haze-venus.html
f.thorpe
CC BY-SA 4.0
2018-05-26T14:14:35.927Z
Surprised this wasn't suggested for moving to Astronomy SE based upon the topic.  Though the atmospheric focus might well truly see more knowledgeable experts attentive around here.
JeopardyTempest
CC BY-SA 4.0
2018-05-26T14:24:51.787Z
@JeopardyTempest I know what you mean. For planetary science type questions, Astronomy, Space Exploration, and Earth Science SE are all potential candidates. I was hoping that "cloud vs. haze" might have a planet-independent answer, or that someone here might know enough about atmospheres to better interpret what's been published about Venus' atmosphere. To many people in Space Exploration SE, atmospheres are just something to get out of as quickly as possible, or to use for aerobraking.
uhoh
CC BY-SA 4.0
2018-06-01T14:12:29.537Z
Thanks to the Earth Science SE for its tolerance for our sister planet !
Cornelis
CC BY-SA 4.0
2018-06-02T11:01:02.560Z
@uhoh  Clouds and haze are aerosols, so what do you mean with "water in the form of an aerosol" ?
Cornelis
CC BY-SA 4.0
2018-06-02T11:16:21.347Z
@uhoh  And what do you mean with "aerosols based on water" ? Aerosols here are diluted sulfuric acid droplets in the mainly CO2 gas.
Cornelis
CC BY-SA 4.0
2018-06-02T12:03:32.117Z
@Conelisinspace I'd always thought aerosols involved droplets of liquids, apparently not! I'll have to figure out a better way to word the question. Any suggestions?
uhoh
CC BY-SA 4.0
2018-06-02T12:45:51.080Z
@uhoh  I think you thought right, but the liquid of the droplets is sulfuric acid diluted with water, so instead of "water in the form of an aerosol" "water as part of an aerosol" could be more exact .
Cornelis
CC BY-SA 4.0
2018-06-04T09:40:23.447Z
@uhoh   Added an important link to my answer.
Cornelis
<atmosphere><clouds>
Difference between sulfuric clouds and sulfuric haze (on Venus)?
uhoh
# Difference between sulfuric clouds and sulfuric haze (on Venus)?

(Asked by: username_0 on 2018-05-11)

In a conversation in comments below [this answer](https://space.stackexchange.com/a/27199/12102) to the question in Space Exploration [Could we see the surface of Venus after the explosion of a H-bomb in its atmosphere?](https://space.stackexchange.com/q/27193/12102) we're speculating about what terms like sulfuric clouds and sulfuric haze mean, and in particular if they are both made of aerosols based on water.

What might be the difference between sulfuric clouds and sulfuric haze, and do both still require water in the form of an aerosol?

[![enter image description here](https://i.sstatic.net/nbWK2.png)](https://i.sstatic.net/nbWK2.png)

**Tags:** atmosphere, clouds

> **Comments:**
> **username_1**: This may be of use: https://www.space.com/5011-mysterious-haze-venus.html  
> **username_2**: Surprised this wasn't suggested for moving to Astronomy SE based upon the topic.  Though the atmospheric focus might well truly see more knowledgeable experts attentive around here.  
> **username_0**: @username_2 I know what you mean. For planetary science type questions, Astronomy, Space Exploration, and Earth Science SE are all potential candidates. I was hoping that "cloud vs. haze" might have a planet-independent answer, or that someone here might know enough about atmospheres to better interpret what's been published about Venus' atmosphere. To many people in Space Exploration SE, atmospheres are just something to get out of as quickly as possible, or to use for aerobraking.  
> **username_3**: Thanks to the Earth Science SE for its tolerance for our sister planet !  
> **username_3**: @username_0  Clouds and haze are aerosols, so what do you mean with "water in the form of an aerosol" ?  
> **username_3**: @username_0  And what do you mean with "aerosols based on water" ? Aerosols here are diluted sulfuric acid droplets in the mainly CO2 gas.  
> **username_0**: @Conelisinspace I'd always thought aerosols involved droplets of liquids, apparently not! I'll have to figure out a better way to word the question. Any suggestions?  
> **username_3**: @username_0  I think you thought right, but the liquid of the droplets is sulfuric acid diluted with water, so instead of "water in the form of an aerosol" "water as part of an aerosol" could be more exact .  
> **username_3**: @username_0   Added an important link to my answer.  

---

## 1 answers

### Answer by username_3 on 2018-05-12. Score: 4 | Accepted answer

According to Wikipedia, [**haze**](https://en.wikipedia.org/wiki/Haze) is an atmospheric phenomenon in which dry particulates obscure the clarity of the sky.

Whereas haze is thought of as a phenomenon of dry air, mist formation is a phenomenon of humid air.

However, haze particles may act as condensation nuclei for the subsequent formation of mist droplets; such forms of haze are known as "wet haze".

In meteorological literature, the word haze is generally used to denote visibility-reducing aerosols of the **wet** type.

According to Wikipedia,  [**a cloud**](https://en.wikipedia.org/wiki/Cloud) is an aerosol with a **visible** mass of liquid droplets, frozen crystals or particals suspended in the atmosphere, and the droplets **don't have to be made of water.**

[This article](http://www.hou.usra.edu/meetings/venus2014/pdf/6005.pdf) states that standard cloud models for Venus consider that all clouds and hazes are composed of liquid droplets of sulfuric acid mixed with water, with sulfuric acid making accounting for 75% to 96% by weight of the cloud composition.
However, other minor constituents may make up the cloud particles.

**Clearly regarding the mixture of water and sulfuric acid there is no distinction between clouds and hazes on Venus.**

In [another article](https://www.lpi.usra.edu/vexag/meetings/archive/vexag_4th/nov_2007/presentations/toon.pdf) it can be seen on images that the altitude from 30-48 km of the atmosphere of Venus is named "the thin haze region ", whereas
the altitude from 48-50 km is called "lower cloud region ".

The figure on page 14 of [the dissertation of Yeon Joo Lee](https://www.mps.mpg.de/phd/theses/venus-cloud-structure-and-radiative-energy-balance-of-the-mesosphere.pdf) also shows that below the cloud layers there is this "thin haze region" which has almost a thousandfold less [extinction coëfficiënt](https://en.wikipedia.org/wiki/Extinction_coefficient) than the clouds above it.

**Apparently this huge difference in absorbing the light explains the difference and appearance between sulfuric clouds and sulfuric haze on Venus.**

Figure 4 of Bullock and Grinspoon 2001 (paywalled) [The Recent Evolution of Climate on Venus](https://www.sciencedirect.com/science/article/pii/S0019103500965709) (Icarus 150, 1, Mar. 2001, pp 19-37) shows the abundances of H$\_2$SO$\_4$ and H$\_2$O in the cloud region of the atmosphere of Venus. A non-paywalled version can be found with an internet search, but since it does not use https I won't include the link explicitly here.

[![Fig 4 Bullock & Grinspoon 2001 Venus aerosols](https://i.sstatic.net/wqRfx.png)](https://i.sstatic.net/wqRfx.png)

Explicitely it shows H$\_2$SO$\_4$ as a gas in the thin haze region and only in the cloud region there is a mixture of water and sulfuric acid liquid.

> **Comments:**
> **username_0**: Thanks for your answer! When you say "According to Wikipedia" it would be a really good idea to add a link directly to the section where it says it, and also add a block quote in case the link breaks. We can't just "read Wikipedia to the OP" in an answer in Stack Exchange.  
> **username_3**: @ Why a link if i already gave the necessary information ? It's not that much effort to look for haze and wiki on internet .More important to me, do you agree with my answer, and is maybe a further distinction that clouds have a shape and hazes don't ?  
> **username_0**: That's just good practice throughout most science and fact-based SE sites. One reason, though there are others, is that it helps people know you are not making stuff up (which you are of course not in this case). Adding links to sources of quoted and cited information is almost standard, you can look through other answers and see it's almost universal.  
> **username_0**: Wikipedia is really, *really,* **really** big! You might have read this in an article about meteorology, or one about clouds, or one about pollution, or one about haze, or one about sulfuric haze, or one about Venus, or one about atmosphere of Venus... "According to Wikipedia" by itself is not really helpful because it's impossible to check.  
> **username_3**: Haze is a distinct article on Wikipedia, it's just logical to look for that !  
> **username_0**: Okay, I'll stop recommending how to write good Stack Exchange answers.  
> **username_3**: I appreciate your recommending, but i just wanted to explain my point of view. So since it's just good practice, i think you are allowed to edit my answer. It's good to have exchange of thoughts on this site !  
> **username_3**: @username_0  I'm sorry if i offended you, i can be rather unwilling sometimes. So i've added a link on my answer. And please, don't stop recommending how to write good Stack Exchange answers, we might learn from them !  
> **username_0**: Oh don't worry about it! In SE it's sometimes difficult to judge when someone is being helpful or just giving a hard time. When I first started I got "beat up" by some people who treat SE as a contact sport rather than the intellectual Smörgåsbord that it is, or at least can be, so it took a while to learn to be defensive, and then longer to un-learn it.  
> **username_3**: @username_0  I came upon an article that gave me more insight in the atmosphere of Venus so i've changed the conclusion in my answer  
> **username_0**: It looks great! This is a really well-researched, reasoned, and explained answer.  
> **username_0**: I adjusted the wording of the reference and added the plot, I hope you don't mind. This way if, or *when* the link eventually rots, the answer is still useful.  
> **username_3**: Thank you for editing, it certainly looks greater now. Much is still unknown, like the possible condensation nuclei.  
> **username_3**: @username_0  I've used your "Fig. 4 " to embellish my answer on[ this question] (http://space.stackexchange.com/questions/27467/is-really-almost-all-the-water-in-the-atmosphere-of-venus-above-the-clouds)  
> **username_3**: @username_0  How can H2SO4 ,b.p. 337 C, be a gas at 45 km, 110 C and 2 atm. ?  Is the link already rotting ?  
> **username_0**: Why don't you ask that as a new question? Include the link and quote the passage as a block quote (use the `>` symbol) you have a choice of SE sites. There is Chemistry SE, but they are a little tougher on new users so if you decide to write it there, be thorough in your question.  
> **username_3**: Let us [continue this discussion in chat](https://chat.stackexchange.com/rooms/78347/discussion-between-conelisinspace-and-username_0).  
> **username_3**: H2SO4 can be a gas beneath the lower cloud boundary because  the partial pressure of it with 3 ppm is of course magnitudes lower than the 2 atm. of the surrounding CO2. I've changed the answer to that extent that the extinction coëfficiënt explains the difference between clouds and haze better  than mass loading does.  

---

