<p>The term you are looking for is <a href="http://www.atmos.washington.edu/Atlas/oro.html" rel="nofollow noreferrer">orographic clouds</a>.
specifically the föhn wall type created by föhn winds. </p>

CC BY-SA 3.0
2017-05-28T17:14:42.840Z
I'm not sure about this. The stuff I've photographed just pours down the side of the mountains, almost stuck to them. It doesn't really look like a cloud as much as really think, heavy fog, as suggested in comments above. Of course there may not be a clear distinction between those two in all cases, I don't know really. High fog vs low clouds... The graphic in your link shows an altitude cut-off (red dashed line) https://i.sstatic.net/fV4GI.jpg
uhoh
CC BY-SA 3.0
2017-05-28T17:15:03.297Z
Then again @DavidHammen 's [link above](https://earthscience.stackexchange.com/questions/10478/#comment20675_10478) shows a photo that looks almost identical, in a similar climate also near sea level, so perhaps this is the right term after all!
uhoh
CC BY-SA 3.0
2017-05-28T18:23:04.553Z
@uhoh its not an altitude mark as much as it is change in height, its not a set height be varies with temp and pressure. The shape of the cloud varies a lot based on the local wind patterns. In your photo notice how it pours over then disappears as it drops below the condensation level.
John
CC BY-SA 3.0
2017-05-28T14:12:51.550Z
2017-05-28T16:24:28.257Z
2017-05-28T16:24:28.257Z
John
<p>Effect like this may be caused by temperature inversion. When warm air/cloud runs into barrier like a hill or mountain it raises (convection) and temperature drops (adiabatic change). Then you see an effect like this "pouring cloud". When it comes down it may cause smog when city is polluted.</p>

CC BY-SA 3.0
2017-05-28T12:37:15.477Z
Thanks. So you think the wind was bringing very moist air from behind the mountains - roughly from the south?
uhoh
CC BY-SA 3.0
2017-05-28T13:01:56.143Z
Yes, humidity will probably rise slightly.
aglango
CC BY-SA 3.0
2017-05-28T12:02:58.767Z
2017-05-28T12:02:58.767Z
aglango
<p>The term used by the American Meteorological Society is <a href="http://glossary.ametsoc.org/wiki/Orographic_fog" rel="nofollow noreferrer">orographic fog</a>. A perhaps more descriptive name is "orographic waterfall cloud".</p>

<p>Prevailing winds can force air to flow upwards over rising terrain. The rising air cools more or less adiabatically, and this can in turn result in clouds. The nature of the orographic clouds (orographic: "related to mountains") that result vary greatly.</p>

<p>In arid regions, orographic clouds can form lenticular clouds that look <a href="https://apod.nasa.gov/apod/ap121104.html" rel="nofollow noreferrer">amazingly</a> <a href="https://apod.nasa.gov/apod/ap030326.html" rel="nofollow noreferrer">like</a> <a href="https://apod.nasa.gov/apod/ap150302.html" rel="nofollow noreferrer">UFOs</a> (three links). Unstable conditions can result in wave clouds, where an obstruction causes a cloud after cloud after cloud downwind of the obstruction. Even <a href="https://earthobservatory.nasa.gov/Features/CloudsGallery/images/sgeorgia_tmo_2015331_lrg.jpg" rel="nofollow noreferrer">icebergs can cause wave clouds</a>. Another form of orographic cloud is a banner cloud, where a cloud flies like a banner downwind of a mountain:</p>

<p><a href="https://i.sstatic.net/AbOMD.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/AbOMD.jpg" alt="Banner cloud flying behind the Matterhorn"></a><br>
<sup>Source: <a href="https://commons.wikimedia.org/wiki/File:Banner_clouds.jpg" rel="nofollow noreferrer">https://commons.wikimedia.org/wiki/File:Banner_clouds.jpg</a> . Copyright Zacharie Grossen, license CC BY-SA 3.0</sup></p>

<p>This is getting closer to an orographic fog. Climbers on the Matterhorn oftentimes experience that cloud, firsthand. Even closer to home is Table Mountain near Cape Town, South Africa.</p>

<p><a href="https://i.sstatic.net/Xmq32.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/Xmq32.jpg" alt="Table Mountain, with a table cloth cloud descending from it"></a><br>
<sup>Source: <a href="https://commons.wikimedia.org/wiki/File:Cape_Town,_Table_Mountain,_Table_Cloth.jpg" rel="nofollow noreferrer">https://commons.wikimedia.org/wiki/File:Cape_Town,_Table_Mountain,_Table_Cloth.jpg</a>. Copyright KodachromeFan, license CC BY-SA 3.0</sup></p>

<p>This is an orographic fog. (Table Mountain can also create some rather spectacular lenticular clouds.) Another example of an orographic fog is detailed in the article "<a href="http://www.hko.gov.hk/education/article_e.htm?title=ele_00484" rel="nofollow noreferrer">Waterfall-like Orographic Clouds</a>".</p>

<p>The conditions needed to form an orographic fog include</p>

<ul>
<li>Prevailing winds that force air to blow upwards over an obstruction, with the orographic fog flowing downwind from the obstruction.</li>
<li>The flowing air must be sufficiently humid. Without this condition, you might see a very cool looking lenticular cloud, but you won't see a banner cloud or an orographic fog.</li>
<li>The flowing air must be sufficiently cool. Humid air at the same pressure and temperature of arid air is less dense than is that arid air. The flowing humid air has to be fairly cool for the flow to be downward downwind of the obstruction.</li>
<li>The flow has to be fairly slow (low Reynolds number) and uniform (low Froude number). Otherwise, a wave cloud or banner cloud will result.</li>
</ul>

CC BY-SA 3.0
2017-05-29T04:15:40.033Z
Note to potential editors: I linked to multiple images via hypertext links rather than embedded images. The linked images are copyrighted; please do not insert those images without permission of the copyright holder.
David Hammen
CC BY-SA 3.0
2017-05-29T04:27:17.390Z
Note also: I could have gotten Reynolds number and Froude number reversed. Fluid mechanics! I wouldn't be surprised if Weber's number also comes into play.
David Hammen
CC BY-SA 3.0
2017-05-29T04:58:39.513Z
OK they have both a descriptive name and some interesting science behind them, thanks! I may try to figure out where those clouds are forming and see if I can get up close some time.
uhoh
CC BY-SA 4.0
2019-01-10T05:05:11.550Z
I certainly learned something, great answer :)
JeopardyTempest
CC BY-SA 3.0
2017-05-29T04:15:29.437Z
2017-05-29T04:15:29.437Z
David Hammen
<p>I snapped this photo with my phone flat against the window of a bus, facing south while traveling west across a bridge in New Taipei City. I'd say it was at about 24.995N, 121.438E. It was about 14:00 local time, 28-05-2017, a cool day, roughly 20C outdoors but I don't know the temperature in the mountains. The overall bluish/greenish hue is the result of the tinting of the bus' window.</p>

<p>Is there a name for this "pouring clouds" effect? </p>

<p><a href="https://i.sstatic.net/PC04u.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/PC04u.png" alt="enter image description here"></a></p>

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

<p><a href="https://i.sstatic.net/vsg4S.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/vsg4S.jpg" alt="enter image description here"></a></p>

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

CC BY-SA 3.0
2017-05-28T08:01:12.283Z
My only (rather simplistic) answer is... fog!  Hear me out... fog is typically dense due to it being colder... so it can potentially pour downwards from higher sources (not all too different from CO2 sinking in cool videos like [this](https://www.youtube.com/watch?v=8tHOVVgGkpk)).  Can't think of any special name it'd have, just a cool effect :-)
JeopardyTempest
CC BY-SA 3.0
2017-05-28T16:55:22.713Z
Combining both answers to date: http://www.hko.gov.hk/education/article_e.htm?title=ele_00484 .
David Hammen
CC BY-SA 3.0
2017-05-28T17:17:22.623Z
@DavidHammen that certainly looks like exactly the same thing to me! "Waterfall-like Orographic Clouds" or just "Waterfall Clouds" seems to be the best answer.
uhoh
CC BY-SA 3.0
2017-05-28T17:39:54.613Z
@DavidHammen: if you were to write you comment as an answer I'd up vote it.
Fred
CC BY-SA 3.0
2017-05-30T19:46:44.790Z
You see these very frequently in the San Francisco peninsula when there's dense fog on the coast that pours over the coastal hills.
BillDOe
<clouds><terminology><humidity>
Is there a name for these "pouring" clouds?
uhoh
# Is there a name for these "pouring" clouds?

(Asked by: username_0 on 2017-05-28)

I snapped this photo with my phone flat against the window of a bus, facing south while traveling west across a bridge in New Taipei City. I'd say it was at about 24.995N, 121.438E. It was about 14:00 local time, 28-05-2017, a cool day, roughly 20C outdoors but I don't know the temperature in the mountains. The overall bluish/greenish hue is the result of the tinting of the bus' window.

Is there a name for this "pouring clouds" effect?

[![enter image description here](https://i.sstatic.net/PC04u.png)](https://i.sstatic.net/PC04u.png)

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

[![enter image description here](https://i.sstatic.net/vsg4S.jpg)](https://i.sstatic.net/vsg4S.jpg)

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

**Tags:** clouds, terminology, humidity

> **Comments:**
> **username_1**: My only (rather simplistic) answer is... fog!  Hear me out... fog is typically dense due to it being colder... so it can potentially pour downwards from higher sources (not all too different from CO2 sinking in cool videos like [this](https://www.youtube.com/watch?v=8tHOVVgGkpk)).  Can't think of any special name it'd have, just a cool effect :-)  
> **username_2**: Combining both answers to date: http://www.hko.gov.hk/education/article_e.htm?title=ele_00484 .  
> **username_0**: @username_2 that certainly looks like exactly the same thing to me! "Waterfall-like Orographic Clouds" or just "Waterfall Clouds" seems to be the best answer.  
> **username_3**: @username_2: if you were to write you comment as an answer I'd up vote it.  
> **username_4**: You see these very frequently in the San Francisco peninsula when there's dense fog on the coast that pours over the coastal hills.  

---

## 3 answers

### Answer by username_2 on 2017-05-29. Score: 3 | Accepted answer

The term used by the American Meteorological Society is [orographic fog](http://glossary.ametsoc.org/wiki/Orographic_fog). A perhaps more descriptive name is "orographic waterfall cloud".

Prevailing winds can force air to flow upwards over rising terrain. The rising air cools more or less adiabatically, and this can in turn result in clouds. The nature of the orographic clouds (orographic: "related to mountains") that result vary greatly.

In arid regions, orographic clouds can form lenticular clouds that look [amazingly](https://apod.nasa.gov/apod/ap121104.html) [like](https://apod.nasa.gov/apod/ap030326.html) [UFOs](https://apod.nasa.gov/apod/ap150302.html) (three links). Unstable conditions can result in wave clouds, where an obstruction causes a cloud after cloud after cloud downwind of the obstruction. Even [icebergs can cause wave clouds](https://earthobservatory.nasa.gov/Features/CloudsGallery/images/sgeorgia_tmo_2015331_lrg.jpg). Another form of orographic cloud is a banner cloud, where a cloud flies like a banner downwind of a mountain:

[![Banner cloud flying behind the Matterhorn](https://i.sstatic.net/AbOMD.jpg)](https://i.sstatic.net/AbOMD.jpg)  
Source: <https://commons.wikimedia.org/wiki/File:Banner_clouds.jpg> . Copyright Zacharie Grossen, license CC BY-SA 3.0

This is getting closer to an orographic fog. Climbers on the Matterhorn oftentimes experience that cloud, firsthand. Even closer to home is Table Mountain near Cape Town, South Africa.

[![Table Mountain, with a table cloth cloud descending from it](https://i.sstatic.net/Xmq32.jpg)](https://i.sstatic.net/Xmq32.jpg)  
Source: <https://commons.wikimedia.org/wiki/File:Cape_Town,_Table_Mountain,_Table_Cloth.jpg>. Copyright KodachromeFan, license CC BY-SA 3.0

This is an orographic fog. (Table Mountain can also create some rather spectacular lenticular clouds.) Another example of an orographic fog is detailed in the article "[Waterfall-like Orographic Clouds](http://www.hko.gov.hk/education/article_e.htm?title=ele_00484)".

The conditions needed to form an orographic fog include

* Prevailing winds that force air to blow upwards over an obstruction, with the orographic fog flowing downwind from the obstruction.
* The flowing air must be sufficiently humid. Without this condition, you might see a very cool looking lenticular cloud, but you won't see a banner cloud or an orographic fog.
* The flowing air must be sufficiently cool. Humid air at the same pressure and temperature of arid air is less dense than is that arid air. The flowing humid air has to be fairly cool for the flow to be downward downwind of the obstruction.
* The flow has to be fairly slow (low Reynolds number) and uniform (low Froude number). Otherwise, a wave cloud or banner cloud will result.

> **Comments:**
> **username_2**: Note to potential editors: I linked to multiple images via hypertext links rather than embedded images. The linked images are copyrighted; please do not insert those images without permission of the copyright holder.  
> **username_2**: Note also: I could have gotten Reynolds number and Froude number reversed. Fluid mechanics! I wouldn't be surprised if Weber's number also comes into play.  
> **username_0**: OK they have both a descriptive name and some interesting science behind them, thanks! I may try to figure out where those clouds are forming and see if I can get up close some time.  
> **username_1**: I certainly learned something, great answer :)  

---

### Answer by username_5 on 2017-05-28. Score: 2

The term you are looking for is [orographic clouds](http://www.atmos.washington.edu/Atlas/oro.html).
specifically the föhn wall type created by föhn winds.

> **Comments:**
> **username_0**: I'm not sure about this. The stuff I've photographed just pours down the side of the mountains, almost stuck to them. It doesn't really look like a cloud as much as really think, heavy fog, as suggested in comments above. Of course there may not be a clear distinction between those two in all cases, I don't know really. High fog vs low clouds... The graphic in your link shows an altitude cut-off (red dashed line) https://i.sstatic.net/fV4GI.jpg  
> **username_0**: Then again @username_2 's [link above](https://earthscience.stackexchange.com/questions/10478/#comment20675_10478) shows a photo that looks almost identical, in a similar climate also near sea level, so perhaps this is the right term after all!  
> **username_5**: @username_0 its not an altitude mark as much as it is change in height, its not a set height be varies with temp and pressure. The shape of the cloud varies a lot based on the local wind patterns. In your photo notice how it pours over then disappears as it drops below the condensation level.  

---

### Answer by username_6 on 2017-05-28. Score: 2

Effect like this may be caused by temperature inversion. When warm air/cloud runs into barrier like a hill or mountain it raises (convection) and temperature drops (adiabatic change). Then you see an effect like this "pouring cloud". When it comes down it may cause smog when city is polluted.

> **Comments:**
> **username_0**: Thanks. So you think the wind was bringing very moist air from behind the mountains - roughly from the south?  
> **username_6**: Yes, humidity will probably rise slightly.  

---

