<p>Dust storms or haboobs traveling over seas and oceans is a common phenomenon, and will occur in any desert (having loose soil and sand) with a coastline. Such deserts include the Sahara, the Arabian desert, parts of the deserts of Australia, etc.</p>
<p>Haboobs are caused by collapsing thunderstorms, when the downdraft of cooler air crashes on the ground and blow away the loose and dry topsoil. The conditions required for the formation of haboobs is those required for the formation of thunderstorms in a desert, i.e., solar insolation heating up surface air and creates an updraft of hot air, which cools down in the higher altitudes and creates a downdraft over time, slamming a column of cooler air on the dry desert surface. This downdraft then carries away the blown dust in directions determined by the air pressure difference. In coastal deserts, the blown dust may often be carried over to the sea or ocean.</p>
<p>In fact, dust storms, or more broadly dust clouds, crossing oceans constitutes one of the most critical processes shaping up the current environment of the earth. This particular process is the <a href="https://en.wikipedia.org/wiki/Saharan_Air_Layer" rel="nofollow noreferrer">Saharan air layer</a>, which carries tens of millions of tons of sand and minerals from the Sahara over the Atlantic ocean all the way to the Amazons in South America. <a href="https://www.nasa.gov/content/goddard/nasa-satellite-reveals-how-much-saharan-dust-feeds-amazon-s-plants" rel="nofollow noreferrer">The nutrients play a key role in fertilizing the Amazon rain forest</a>. <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007GL031538" rel="nofollow noreferrer">The particles in the dust cloud cools the Atlantic ocean</a>, and <a href="https://archive.org/details/impactsaharanair00veld" rel="nofollow noreferrer">hinders the formation and intensification of cyclones in the Atlantic</a>. This process often creates gigantic dust storms or dust cloud spread over thousands of kilometers across, clearly <a href="https://www.youtube.com/watch?v=ygulQJoIe2Y" rel="nofollow noreferrer">observable and studied using satellite imagery</a>.</p>
<p>Some of the news related to recent such Saharan dust storms crossing the Atlantic, with associated imagery:</p>
<ul>
<li><a href="https://www.independent.co.uk/climate-change/sahara-dust-storm-atlantic-image-b1996665.html" rel="nofollow noreferrer">Satellite images show 4,000km-long Saharan dust cloud across Atlantic Ocean</a></li>
<li><a href="https://www.theatlantic.com/science/archive/2020/06/saharan-dust-storms-giving-earth-life/613441/" rel="nofollow noreferrer">A Giant Dust Storm Is Heading Across the Atlantic</a></li>
<li><a href="https://www.severe-weather.eu/news/new-saharan-dust-cloud-atlantic-united-states-forecast-fa/" rel="nofollow noreferrer">A new large Saharan dust cloud is moving over the Atlantic Ocean, forecast to reach the Caribbean and the southeastern United States by the end of the week</a></li>
</ul>
<p>However, as can be observed from the images of the Saharan dust storms, formation of shelf clouds over the dust storms are rare for them. This is because the formation of such clouds require cooler temperature and sufficient moisture, which would not be available in the usual Saharan dust storms over the Atlantic. From the <a href="https://en.wikipedia.org/wiki/Arcus_cloud" rel="nofollow noreferrer">Wikipedia page</a>:</p>
<blockquote>
<p>They most frequently form along the leading edge or gust fronts of thunderstorms; some of the most dramatic arcus formations mark the gust fronts of derecho-producing convective systems. Roll clouds may also arise in the absence of thunderstorms, forming along the shallow cold air currents of some sea breeze boundaries and cold fronts.</p>
</blockquote>
<p>The formation of <a href="https://en.wikipedia.org/wiki/Cold_front" rel="nofollow noreferrer">cold fronts</a> is often associated with Australian dust storms (<a href="https://www.sciencedirect.com/science/article/pii/034181629500026O" rel="nofollow noreferrer">1</a>, <a href="https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.1072" rel="nofollow noreferrer">2</a>). And such storms occurring in especially the north-western coastal deserts of Australia will have adequate moisture from the Indian Ocean and the cooler air required. Due to this, such spectacular but rare phenomenon is likely to occur more in the Australian deserts compared to the Saharan or the Arabian deserts, which are often too dry for the formation of such clouds.</p>
<p>So the conditions required for the occurrence of this phenomenon are:</p>
<ul>
<li>a coastal <a href="https://en.wikipedia.org/wiki/Desert_climate#Hot_desert_climates" rel="nofollow noreferrer">hot desert</a> with loose surface soil,</li>
<li>temperature not hot enough so that the dust storm does not lift over cooler <a href="https://en.wikipedia.org/wiki/Marine_layer" rel="nofollow noreferrer">marine air</a> and becomes a dust cloud, as happens for the <a href="https://en.wikipedia.org/wiki/Saharan_Air_Layer#Creation" rel="nofollow noreferrer">Saharan air layer</a>, where even the temperature of the downdraft is so high that the resulting dust storm lifts over the cooler Atlantic marine air and becomes a dust cloud.</li>
<li>just enough moisture in the environment for the formation of <a href="https://en.wikipedia.org/wiki/Arcus_cloud" rel="nofollow noreferrer">shelf clouds</a>, but not enough to cause rainfall in the thunderstorm, thereby dissipating the dust storm and the clouds over them.</li>
</ul>

CC BY-SA 4.0
2022-02-16T15:44:26.970Z
I'm not so sure the long-range dust transports have much similarity to localized haboobs... one is caused by synoptic wind patterns, the other by thunderstorms with strong downdrafts/outflow.
JeopardyTempest
CC BY-SA 4.0
2022-02-16T15:48:27.030Z
Yes, what is meant by haboobs are more localized weather phenomenon. However, those Saharan dust clouds are also referred to as dust storms, as can be seen in the links. I included them as they are also a type of dust storm traveling over an ocean, and might be found interesting.
joy
CC BY-SA 4.0
2022-02-16T15:50:17.240Z
I'd also suggest that there's no "too hot" factor. The Sahara is too dry to get thunderstorms often. You don't need cool marine air... haboobs are common in AZ, where there's no marine air. Downdraft temperatures aren't high, they **are** the cold air that drives a gust front forward to make haboobs go. And typically you need quite a bit of moisture, as haboobs are typically storm driven... but need dry mid-levels/synoptic ingredients to cause thunderstorm outflow to gust away from the storm. So your third point is kind of correct, but thunderstorms don't dissipate clouds, but drive them. :)
JeopardyTempest
CC BY-SA 4.0
2022-02-16T15:51:31.403Z
But no stress, your answer overall is quite decent.  I had hoped to answer, but didn't have the time, but you covered the details fairly reasonably overall, was just adding constructive criticism/cleaning up a few points.
JeopardyTempest
CC BY-SA 4.0
2022-02-16T15:55:02.987Z
Thank you for your comments, @JeopardyTempest, I also learn from them :) In response to your previous comment, I meant to say that if the relatively cooler air in the downdraft of the dust storm is too hot compared to oceanic marine air, when the dust storm reaches the ocean, it might simply rise above the cooler marine air and not touch the ocean as depicted in the question.
joy
CC BY-SA 4.0
2022-02-16T15:57:45.710Z
And the moisture content in the surrounding environment should be just high enough to form the shelf cloud. Too low moisture and no such shelf cloud forms, as in the case of Saharan or Arabian dust storms crossing the ocean or the seas. Too high moisture, and there might a torrential rainfall dissipating the dust storm and the clouds over it.
joy
CC BY-SA 4.0
2022-02-16T16:14:15.177Z
There needs to be a torrential thunderstorm for the formation of the cold pool that creates a haboob. But the cold air rushes out ahead, so that it's haboob first, then thunderstorm... so there's no issues of the thunderstorm dissipating the haboob. It's true that if instability is too widespread, you can get additional secondary thunderstorm development along the leading edge of the cold pool/outflow... but moisture levels can be very high and still not allow for additional storms. I'd suggest the key factor is more that recent weather has been dry, leading to the looser surface soil you note
JeopardyTempest
CC BY-SA 4.0
2022-02-16T22:01:36.017Z
Thank you for your nicely written and well-sourced answer! Just fyi, the bounty on [this question](https://earthscience.stackexchange.com/q/22661/6031) has also ended but has 17 more hours left of its invisible "grace period" where it can still be awarded.
uhoh
CC BY-SA 4.0
2022-02-17T05:01:42.577Z
@uhoh thank you for your kind words, and thank you for informing me of the other question :) I shall try and see if I can answer that question.
joy
CC BY-SA 4.0
2022-02-17T12:26:10.317Z
Wrote an answer to [that question](https://earthscience.stackexchange.com/q/22661/6031), @uhoh . Could you please see if that resolves the query?
joy
CC BY-SA 4.0
2022-02-17T17:10:01.880Z
Hi @uhoh, I was wondering what are the ways this answer falls short to being the _acceptable_ answer to this question. If you please let me know that, I shall try to address them. Please also let me know the same about my [other answer](https://earthscience.stackexchange.com/a/23542/23207) you awarded bounty.
joy
CC BY-SA 4.0
2022-02-17T20:23:53.827Z
@joy I always wait at least several days if not several weeks before accepting answers. I do that for several reasons. Once you post an answer the question is kicked back into the *active* queue and more people see it. That means there is a chance of additional answers being posted and it gives another chance for people to up vote your answer. After a week or two or three if there are no more answers I may click "accept" and once again the post is kicked back into the active queue, there's again another opportunity for people to see, vote & answer. I just like to keep my posts active/visible.
uhoh
CC BY-SA 4.0
2022-02-17T20:26:52.777Z
@joy Bounties on the other hand come with very strict 7-day timers plus a [24 hour grace period](https://space.meta.stackexchange.com/q/877/12102) where they are invisible to everyone except me. So I have to act on those or they disappear and the reputation I spent disappears and is wasted, and if I want to add a replacement it [must be double](https://space.meta.stackexchange.com/q/888/12102) the previous one. You are obviously a great contributor to Stack Exchange and will enjoy the [privileges that come with increasing reputation thresholds](https://meta.stackexchange.com/a/160292/303080)
uhoh
CC BY-SA 4.0
2022-02-17T22:39:06.683Z
@uhoh thank you so much for your kind and very informative responses, I really appreciate them :) I was just wondering if my answers fell short in any way, so I asked you. But no issues, and thank you again. I shall also wait and see forward to gaining knowledge from others if they post answers to the questions :)
joy
CC BY-SA 4.0
2022-04-24T23:48:59.200Z
...and apparently in that intervening [several days or weeks](https://earthscience.stackexchange.com/questions/22397/is-it-unusual-to-see-haboobs-travel-over-the-indian-ocean-with-shelf-clouds-on-t#comment55288_23539) forgot to come back and accept. *Sorry!*
uhoh
CC BY-SA 4.0
2022-04-25T00:59:08.607Z
Wow thank you @uhoh !
joy
CC BY-SA 4.0
2022-02-16T15:01:22.690Z
2022-02-16T15:19:35.047Z
2022-02-16T15:19:35.047Z
joy
<p>By accident<sup>1</sup> I ended up on the Bytes Daily page <a href="http://bytesdaily.blogspot.com/2013/12/photographs-2013-part-1.html" rel="nofollow noreferrer">Photographs 2013, part 1</a>. I saw an interesting image who's caption reads:</p>
<blockquote>
<p>A white shelf cloud caps brownish dirt from a dust storm, or haboob, as it travels across the Indian Ocean near Onslow on the Western Australia coast in this handout image distributed by fishwrecked.com and taken January 9, 2013.</p>
</blockquote>
<p>Haboob is described in Wikipedia as follows:</p>
<blockquote>
<p>A haboob (Arabic: هَبوب‎, romanized: habūb, lit. 'blasting/drifting') is a type of intense dust storm carried on an atmospheric gravity current, also known as a weather front. <strong>Haboobs occur regularly in dry land area regions</strong> throughout the world.</p>
</blockquote>
<p><strong>Question(s):</strong></p>
<ol>
<li>Is it rare or unusual for haboobs to travel across the Indian Ocean or other oceans?</li>
<li>Is it rarer or more unusual still for shelf clouds to appear over them?</li>
<li>What conditions are necessary to bring all of this about?</li>
</ol>
<p>Video links from the Wikipedia article:</p>
<ul>
<li>YouTube: <a href="https://www.youtube.com/watch?v=Ibpsxr71VVA" rel="nofollow noreferrer">Arizona Haboob!</a></li>
<li>Vimeo: <a href="https://vimeo.com/26045314" rel="nofollow noreferrer">The Phoenix Haboob of July 5th, 2011</a></li>
</ul>
<hr />
<p><sup>1</sup>I was doing a reverse image search looking for a larger size of the photo of Earth, Venus and Mars amidst the rings of Saturn when Cassini was in Saturn's shadow, and ended up on this page.</p>
<hr />
<p><a href="https://i.sstatic.net/br21t.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/br21t.jpg" alt="Bytes Daily, 2013: A white shelf cloud caps brownish dirt from a dust storm, or haboob, as it travels across the Indian Ocean near Onslow on the Western Australia coast in this handout image distributed by fishwrecked.com and taken January 9, 2013." /></a></p>

CC BY-SA 4.0
2021-06-16T01:55:09.023Z
@gansub holy granola that's beautiful! *Lightning too!*
uhoh
CC BY-SA 4.0
2022-02-13T21:47:00.367Z
@gansub there's a bounty... :-)
uhoh
<clouds><atmospheric-dust>
Is it unusual to see haboobs travel over the Indian Ocean with shelf clouds on top? What conditions can bring all of this about?
uhoh
# Is it unusual to see haboobs travel over the Indian Ocean with shelf clouds on top? What conditions can bring all of this about?

(Asked by: username_0 on 2021-06-15)

By accident1 I ended up on the Bytes Daily page [Photographs 2013, part 1](http://bytesdaily.blogspot.com/2013/12/photographs-2013-part-1.html). I saw an interesting image who's caption reads:

> A white shelf cloud caps brownish dirt from a dust storm, or haboob, as it travels across the Indian Ocean near Onslow on the Western Australia coast in this handout image distributed by fishwrecked.com and taken January 9, 2013.

Haboob is described in Wikipedia as follows:

> A haboob (Arabic: هَبوب‎, romanized: habūb, lit. 'blasting/drifting') is a type of intense dust storm carried on an atmospheric gravity current, also known as a weather front. **Haboobs occur regularly in dry land area regions** throughout the world.

**Question(s):**

1. Is it rare or unusual for haboobs to travel across the Indian Ocean or other oceans?
2. Is it rarer or more unusual still for shelf clouds to appear over them?
3. What conditions are necessary to bring all of this about?

Video links from the Wikipedia article:

* YouTube: [Arizona Haboob!](https://www.youtube.com/watch?v=Ibpsxr71VVA)
* Vimeo: [The Phoenix Haboob of July 5th, 2011](https://vimeo.com/26045314)

---

1I was doing a reverse image search looking for a larger size of the photo of Earth, Venus and Mars amidst the rings of Saturn when Cassini was in Saturn's shadow, and ended up on this page.

---

[![Bytes Daily, 2013: A white shelf cloud caps brownish dirt from a dust storm, or haboob, as it travels across the Indian Ocean near Onslow on the Western Australia coast in this handout image distributed by fishwrecked.com and taken January 9, 2013.](https://i.sstatic.net/br21t.jpg)](https://i.sstatic.net/br21t.jpg)

**Tags:** clouds, atmospheric-dust

> **Comments:**
> **username_0**: @gansub holy granola that's beautiful! *Lightning too!*  
> **username_0**: @gansub there's a bounty... :-)  

---

## 1 answers

### Answer by username_1 on 2022-02-16. Score: 4 | Accepted answer

Dust storms or haboobs traveling over seas and oceans is a common phenomenon, and will occur in any desert (having loose soil and sand) with a coastline. Such deserts include the Sahara, the Arabian desert, parts of the deserts of Australia, etc.

Haboobs are caused by collapsing thunderstorms, when the downdraft of cooler air crashes on the ground and blow away the loose and dry topsoil. The conditions required for the formation of haboobs is those required for the formation of thunderstorms in a desert, i.e., solar insolation heating up surface air and creates an updraft of hot air, which cools down in the higher altitudes and creates a downdraft over time, slamming a column of cooler air on the dry desert surface. This downdraft then carries away the blown dust in directions determined by the air pressure difference. In coastal deserts, the blown dust may often be carried over to the sea or ocean.

In fact, dust storms, or more broadly dust clouds, crossing oceans constitutes one of the most critical processes shaping up the current environment of the earth. This particular process is the [Saharan air layer](https://en.wikipedia.org/wiki/Saharan_Air_Layer), which carries tens of millions of tons of sand and minerals from the Sahara over the Atlantic ocean all the way to the Amazons in South America. [The nutrients play a key role in fertilizing the Amazon rain forest](https://www.nasa.gov/content/goddard/nasa-satellite-reveals-how-much-saharan-dust-feeds-amazon-s-plants). [The particles in the dust cloud cools the Atlantic ocean](https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2007GL031538), and [hinders the formation and intensification of cyclones in the Atlantic](https://archive.org/details/impactsaharanair00veld). This process often creates gigantic dust storms or dust cloud spread over thousands of kilometers across, clearly [observable and studied using satellite imagery](https://www.youtube.com/watch?v=ygulQJoIe2Y).

Some of the news related to recent such Saharan dust storms crossing the Atlantic, with associated imagery:

* [Satellite images show 4,000km-long Saharan dust cloud across Atlantic Ocean](https://www.independent.co.uk/climate-change/sahara-dust-storm-atlantic-image-b1996665.html)
* [A Giant Dust Storm Is Heading Across the Atlantic](https://www.theatlantic.com/science/archive/2020/06/saharan-dust-storms-giving-earth-life/613441/)
* [A new large Saharan dust cloud is moving over the Atlantic Ocean, forecast to reach the Caribbean and the southeastern United States by the end of the week](https://www.severe-weather.eu/news/new-saharan-dust-cloud-atlantic-united-states-forecast-fa/)

However, as can be observed from the images of the Saharan dust storms, formation of shelf clouds over the dust storms are rare for them. This is because the formation of such clouds require cooler temperature and sufficient moisture, which would not be available in the usual Saharan dust storms over the Atlantic. From the [Wikipedia page](https://en.wikipedia.org/wiki/Arcus_cloud):

> They most frequently form along the leading edge or gust fronts of thunderstorms; some of the most dramatic arcus formations mark the gust fronts of derecho-producing convective systems. Roll clouds may also arise in the absence of thunderstorms, forming along the shallow cold air currents of some sea breeze boundaries and cold fronts.

The formation of [cold fronts](https://en.wikipedia.org/wiki/Cold_front) is often associated with Australian dust storms ([1](https://www.sciencedirect.com/science/article/pii/034181629500026O), [2](https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.1072)). And such storms occurring in especially the north-western coastal deserts of Australia will have adequate moisture from the Indian Ocean and the cooler air required. Due to this, such spectacular but rare phenomenon is likely to occur more in the Australian deserts compared to the Saharan or the Arabian deserts, which are often too dry for the formation of such clouds.

So the conditions required for the occurrence of this phenomenon are:

* a coastal [hot desert](https://en.wikipedia.org/wiki/Desert_climate#Hot_desert_climates) with loose surface soil,
* temperature not hot enough so that the dust storm does not lift over cooler [marine air](https://en.wikipedia.org/wiki/Marine_layer) and becomes a dust cloud, as happens for the [Saharan air layer](https://en.wikipedia.org/wiki/Saharan_Air_Layer#Creation), where even the temperature of the downdraft is so high that the resulting dust storm lifts over the cooler Atlantic marine air and becomes a dust cloud.
* just enough moisture in the environment for the formation of [shelf clouds](https://en.wikipedia.org/wiki/Arcus_cloud), but not enough to cause rainfall in the thunderstorm, thereby dissipating the dust storm and the clouds over them.

> **Comments:**
> **username_2**: I'm not so sure the long-range dust transports have much similarity to localized haboobs... one is caused by synoptic wind patterns, the other by thunderstorms with strong downdrafts/outflow.  
> **username_1**: Yes, what is meant by haboobs are more localized weather phenomenon. However, those Saharan dust clouds are also referred to as dust storms, as can be seen in the links. I included them as they are also a type of dust storm traveling over an ocean, and might be found interesting.  
> **username_2**: I'd also suggest that there's no "too hot" factor. The Sahara is too dry to get thunderstorms often. You don't need cool marine air... haboobs are common in AZ, where there's no marine air. Downdraft temperatures aren't high, they **are** the cold air that drives a gust front forward to make haboobs go. And typically you need quite a bit of moisture, as haboobs are typically storm driven... but need dry mid-levels/synoptic ingredients to cause thunderstorm outflow to gust away from the storm. So your third point is kind of correct, but thunderstorms don't dissipate clouds, but drive them. :)  
> **username_2**: But no stress, your answer overall is quite decent.  I had hoped to answer, but didn't have the time, but you covered the details fairly reasonably overall, was just adding constructive criticism/cleaning up a few points.  
> **username_1**: Thank you for your comments, @username_2, I also learn from them :) In response to your previous comment, I meant to say that if the relatively cooler air in the downdraft of the dust storm is too hot compared to oceanic marine air, when the dust storm reaches the ocean, it might simply rise above the cooler marine air and not touch the ocean as depicted in the question.  
> **username_1**: And the moisture content in the surrounding environment should be just high enough to form the shelf cloud. Too low moisture and no such shelf cloud forms, as in the case of Saharan or Arabian dust storms crossing the ocean or the seas. Too high moisture, and there might a torrential rainfall dissipating the dust storm and the clouds over it.  
> **username_2**: There needs to be a torrential thunderstorm for the formation of the cold pool that creates a haboob. But the cold air rushes out ahead, so that it's haboob first, then thunderstorm... so there's no issues of the thunderstorm dissipating the haboob. It's true that if instability is too widespread, you can get additional secondary thunderstorm development along the leading edge of the cold pool/outflow... but moisture levels can be very high and still not allow for additional storms. I'd suggest the key factor is more that recent weather has been dry, leading to the looser surface soil you note  
> **username_0**: Thank you for your nicely written and well-sourced answer! Just fyi, the bounty on [this question](https://earthscience.stackexchange.com/q/22661/6031) has also ended but has 17 more hours left of its invisible "grace period" where it can still be awarded.  
> **username_1**: @username_0 thank you for your kind words, and thank you for informing me of the other question :) I shall try and see if I can answer that question.  
> **username_1**: Wrote an answer to [that question](https://earthscience.stackexchange.com/q/22661/6031), @username_0 . Could you please see if that resolves the query?  
> **username_1**: Hi @username_0, I was wondering what are the ways this answer falls short to being the _acceptable_ answer to this question. If you please let me know that, I shall try to address them. Please also let me know the same about my [other answer](https://earthscience.stackexchange.com/a/23542/23207) you awarded bounty.  
> **username_0**: @username_1 I always wait at least several days if not several weeks before accepting answers. I do that for several reasons. Once you post an answer the question is kicked back into the *active* queue and more people see it. That means there is a chance of additional answers being posted and it gives another chance for people to up vote your answer. After a week or two or three if there are no more answers I may click "accept" and once again the post is kicked back into the active queue, there's again another opportunity for people to see, vote & answer. I just like to keep my posts active/visible.  
> **username_0**: @username_1 Bounties on the other hand come with very strict 7-day timers plus a [24 hour grace period](https://space.meta.stackexchange.com/q/877/12102) where they are invisible to everyone except me. So I have to act on those or they disappear and the reputation I spent disappears and is wasted, and if I want to add a replacement it [must be double](https://space.meta.stackexchange.com/q/888/12102) the previous one. You are obviously a great contributor to Stack Exchange and will enjoy the [privileges that come with increasing reputation thresholds](https://meta.stackexchange.com/a/160292/303080)  
> **username_1**: @username_0 thank you so much for your kind and very informative responses, I really appreciate them :) I was just wondering if my answers fell short in any way, so I asked you. But no issues, and thank you again. I shall also wait and see forward to gaining knowledge from others if they post answers to the questions :)  
> **username_0**: ...and apparently in that intervening [several days or weeks](https://earthscience.stackexchange.com/questions/22397/is-it-unusual-to-see-haboobs-travel-over-the-indian-ocean-with-shelf-clouds-on-t#comment55288_23539) forgot to come back and accept. *Sorry!*  
> **username_1**: Wow thank you @username_0 !  

---

