<p>In the winter when it's overcast, clouds at night are much brighter or more easily illuminated (unsure if they appear above cities/towns only) than in summer, making them look orange at night. I don't remember ever having seen nights with such clouds in the summer, I only know them from the winter. Why are those clouds so bright/orange only during the winter? Aren't they the same clouds it rains from in the summer?</p>

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2022-12-12T21:23:11.440Z
I think your question is answered [here](https://earthscience.stackexchange.com/a/8414/6057) in the question [Is there a seasonal difference in the average cloud floor?](https://earthscience.stackexchange.com/q/8384/6057)
justCal
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2022-12-13T06:00:29.637Z
your question is a bit unclear to me is this what you are asking https://en.wikipedia.org/wiki/Noctilucent_cloud or do you ask about clouds iluminated from below by the sun or city lights?.please edit the information into your question.
trond hansen
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2022-12-13T06:59:03.137Z
@justCal So the simple answer would be that winter clouds are lower because of the lower temperature. Well, perhaps this and the fact that summer nights are short enough that you hardly ever see low enough clouds that are rarer in summer. This could explain it.
Giovanni
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2022-12-13T07:00:58.537Z
@trondhansen No, I'm asking on normal water clouds at low altitudes when it's overcast. I don't need to edit because the term "overcast" isn't used with noctilucent clouds.
Giovanni
CC BY-SA 4.0
2022-12-13T12:28:03.053Z
Yes, and the orange tint you are noticing may be due to the use of [sodium vapor](https://en.wikipedia.org/wiki/Sodium-vapor_lamp)  street lights.
justCal
CC BY-SA 4.0
2022-12-14T05:03:47.270Z
it looks to me like the answer is,the clouds are easier to see because winter nights are darker than summer nights and that the snow in winter reflects more light to iluminate the clouds from below.
trond hansen
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2022-12-14T06:46:23.510Z
Brighter because there's less moisture in cold air causing reflection, and it "has a higher index of refraction than warm air does". And orange because of the angle of the sunlight (due to the Earth's tilt which is why we have seasons). "*Why is the sky orange in winter?* In winter and at higher latitudes, sunlight passes more tangentially through the earth's atmosphere and travels a greater distance, [and then even more so if it's cold because it has a *higher index of refraction*]. As a result, some of the blue light is scattered away and more of the orange light reaches our eyes."
Mazura
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2022-12-14T07:09:02.613Z
@Mazura Very interesting. Thank you.
Giovanni
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2022-12-17T08:22:51.640Z
Just a note: I don't believe the answer pointed to does a good job of explaining why clouds would be lower.  Cool low-level air tends itself to be stable, hindering cloud formation.  Temperature can drop all the way to saturation... fog... but that can happen in summer or winter at night.  I believe the real key is that moisture is favored to move into the cold air in winter (warm fronts and also warm water bodies in much of winter)  The data in my comment suggests on that question shows that both seasons can see low bases.  But more often in winter.
JeopardyTempest
CC BY-SA 4.0
2022-12-17T08:51:54.523Z
On the other comments: trond - definitely agree snow is a major added reflector that further increases light levels, though I believe the experience is valid even lacking snowcover. Mazura - The OP Gio notes nocturnal, so I believe they're talking about fully nighttime effects, nothing solar (phenomena like https://c.wallhere.com/photos/30/0a/city_night_lights_long_exposure_bright_limburg-629514.jpg!d). And so I think the point is we're talking about reflected light (due to clouds), and that generally thicker clouds (= more water) cause the greater reflection, vs thin clouds doing little
JeopardyTempest
CC BY-SA 4.0
2022-12-17T08:54:14.603Z
@trondhansen are winter nights darker (apart from near the Arctic, where full nights fail to occur at least some of the summer)? Is there spillover sunlight even after astronomical twilight that makes the deep summer nights less dark? I didn't think so, but that'd be quite interesting to know.
JeopardyTempest
CC BY-SA 4.0
2022-12-17T08:55:34.887Z
Giovanni: suggest you do try to take a picture when you see it again (probably should avoid the one I added in the comment as it's a stock image and so copyrighted), think it would help users understand the circumstances you're asking about. But I think I am familiar with what you speak of. And yes bright lights in the winter can really light up the sky. (You should probably also go out and verify that it is local lights reflecting, and so tends to be a city phenomena, so the focus can be just on the question of why!)
JeopardyTempest
CC BY-SA 4.0
2022-12-17T10:46:52.373Z
@JeopardyTempest in scandinavia where i live we do not have astronomical twilight from may and until the beginning of august https://www.timeanddate.com/sun/@9751550 the darkest it get is natical twilight.the definitions of twilight can be found here https://www.weather.gov/lmk/twilight-types
trond hansen
CC BY-SA 4.0
2022-12-17T15:14:23.917Z
@trondhansen: right, I believe the trend the OP points to occurs outside of such regions (though it would be useful to know where you are posting about Giovanni)
JeopardyTempest
CC BY-SA 4.0
2022-12-17T15:55:26.480Z
@JeopardyTempest I can say that it certainly occurs above settlements, and I'm unsure whether it occurs above little-inhabited land too (I usually don't travel at night nor do I often spend nights in rural areas), but I think it occurs mostly over cities and towns. I don't recall such orangeish cloud layers from summer even over cities. If those orange night clouds really occur above settlements only, I wonder why in winter only/mostly.
Giovanni
CC BY-SA 4.0
2022-12-17T15:57:35.040Z
I can't take a picture because I don't visit SE from a mobile.
Giovanni
CC BY-SA 4.0
2022-12-18T10:27:24.877Z
@Giovanni if you have a mobile or camera, you could transfer a photo to the PC you visit SE from?
JeopardyTempest
CC BY-SA 4.0
2022-12-18T10:30:03.400Z
@JeopardyTempest Really, even if I don't have Windows on the mobile?
Giovanni
CC BY-SA 4.0
2022-12-18T10:42:44.100Z
@Giovanni sure, worse comes to worst, you could email yourself a copy of the picture.  But more sophisticated methods like bluetooth transfer or the cloud (Google Drive/Dropbox?) exist.  Or that matter, you can plug android/iphones into computers with the USB cable and directly transfer images and other files.
JeopardyTempest
CC BY-SA 4.0
2022-12-18T16:19:18.470Z
@JeopardyTempest I see. If I see such clouds again, I could make a photo.
Giovanni
<meteorology><clouds><winter>
Why are nocturnal winter clouds so bright or so easily illuminated at night, compared to clouds in the summer?
Giovanni
# Why are nocturnal winter clouds so bright or so easily illuminated at night, compared to clouds in the summer?

(Asked by: username_0 on 2022-12-12)

In the winter when it's overcast, clouds at night are much brighter or more easily illuminated (unsure if they appear above cities/towns only) than in summer, making them look orange at night. I don't remember ever having seen nights with such clouds in the summer, I only know them from the winter. Why are those clouds so bright/orange only during the winter? Aren't they the same clouds it rains from in the summer?

**Tags:** meteorology, clouds, winter

> **Comments:**
> **username_1**: I think your question is answered [here](https://earthscience.stackexchange.com/a/8414/6057) in the question [Is there a seasonal difference in the average cloud floor?](https://earthscience.stackexchange.com/q/8384/6057)  
> **username_2**: your question is a bit unclear to me is this what you are asking https://en.wikipedia.org/wiki/Noctilucent_cloud or do you ask about clouds iluminated from below by the sun or city lights?.please edit the information into your question.  
> **username_0**: @username_1 So the simple answer would be that winter clouds are lower because of the lower temperature. Well, perhaps this and the fact that summer nights are short enough that you hardly ever see low enough clouds that are rarer in summer. This could explain it.  
> **username_0**: @username_2 No, I'm asking on normal water clouds at low altitudes when it's overcast. I don't need to edit because the term "overcast" isn't used with noctilucent clouds.  
> **username_1**: Yes, and the orange tint you are noticing may be due to the use of [sodium vapor](https://en.wikipedia.org/wiki/Sodium-vapor_lamp)  street lights.  
> **username_2**: it looks to me like the answer is,the clouds are easier to see because winter nights are darker than summer nights and that the snow in winter reflects more light to iluminate the clouds from below.  
> **username_3**: Brighter because there's less moisture in cold air causing reflection, and it "has a higher index of refraction than warm air does". And orange because of the angle of the sunlight (due to the Earth's tilt which is why we have seasons). "*Why is the sky orange in winter?* In winter and at higher latitudes, sunlight passes more tangentially through the earth's atmosphere and travels a greater distance, [and then even more so if it's cold because it has a *higher index of refraction*]. As a result, some of the blue light is scattered away and more of the orange light reaches our eyes."  
> **username_0**: @username_3 Very interesting. Thank you.  
> **username_4**: Just a note: I don't believe the answer pointed to does a good job of explaining why clouds would be lower.  Cool low-level air tends itself to be stable, hindering cloud formation.  Temperature can drop all the way to saturation... fog... but that can happen in summer or winter at night.  I believe the real key is that moisture is favored to move into the cold air in winter (warm fronts and also warm water bodies in much of winter)  The data in my comment suggests on that question shows that both seasons can see low bases.  But more often in winter.  
> **username_4**: On the other comments: username_2 - definitely agree snow is a major added reflector that further increases light levels, though I believe the experience is valid even lacking snowcover. username_3 - The OP Gio notes nocturnal, so I believe they're talking about fully nighttime effects, nothing solar (phenomena like https://c.wallhere.com/photos/30/0a/city_night_lights_long_exposure_bright_limburg-629514.jpg!d). And so I think the point is we're talking about reflected light (due to clouds), and that generally thicker clouds (= more water) cause the greater reflection, vs thin clouds doing little  
> **username_4**: @username_2 are winter nights darker (apart from near the Arctic, where full nights fail to occur at least some of the summer)? Is there spillover sunlight even after astronomical twilight that makes the deep summer nights less dark? I didn't think so, but that'd be quite interesting to know.  
> **username_4**: username_0: suggest you do try to take a picture when you see it again (probably should avoid the one I added in the comment as it's a stock image and so copyrighted), think it would help users understand the circumstances you're asking about. But I think I am familiar with what you speak of. And yes bright lights in the winter can really light up the sky. (You should probably also go out and verify that it is local lights reflecting, and so tends to be a city phenomena, so the focus can be just on the question of why!)  
> **username_2**: @username_4 in scandinavia where i live we do not have astronomical twilight from may and until the beginning of august https://www.timeanddate.com/sun/@9751550 the darkest it get is natical twilight.the definitions of twilight can be found here https://www.weather.gov/lmk/twilight-types  
> **username_4**: @username_2: right, I believe the trend the OP points to occurs outside of such regions (though it would be useful to know where you are posting about username_0)  
> **username_0**: @username_4 I can say that it certainly occurs above settlements, and I'm unsure whether it occurs above little-inhabited land too (I usually don't travel at night nor do I often spend nights in rural areas), but I think it occurs mostly over cities and towns. I don't recall such orangeish cloud layers from summer even over cities. If those orange night clouds really occur above settlements only, I wonder why in winter only/mostly.  
> **username_0**: I can't take a picture because I don't visit SE from a mobile.  
> **username_4**: @username_0 if you have a mobile or camera, you could transfer a photo to the PC you visit SE from?  
> **username_0**: @username_4 Really, even if I don't have Windows on the mobile?  
> **username_4**: @username_0 sure, worse comes to worst, you could email yourself a copy of the picture.  But more sophisticated methods like bluetooth transfer or the cloud (Google Drive/Dropbox?) exist.  Or that matter, you can plug android/iphones into computers with the USB cable and directly transfer images and other files.  
> **username_0**: @username_4 I see. If I see such clouds again, I could make a photo.  

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## 0 answers

