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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?

Giovanni
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    I think your question is answered here in the question Is there a seasonal difference in the average cloud floor? – justCal Dec 12 '22 at 21:23
  • 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 Dec 13 '22 at 06:00
  • @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 Dec 13 '22 at 06:59
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    @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 Dec 13 '22 at 07:00
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    Yes, and the orange tint you are noticing may be due to the use of sodium vapor street lights. – justCal Dec 13 '22 at 12:28
  • 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 Dec 14 '22 at 05:03
  • 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 Dec 14 '22 at 06:46
  • @Mazura Very interesting. Thank you. – Giovanni Dec 14 '22 at 07:09
  • 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 Dec 17 '22 at 08:22
  • 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 Dec 17 '22 at 08:51
  • @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 Dec 17 '22 at 08:54
  • 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 Dec 17 '22 at 08:55
  • @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 Dec 17 '22 at 10:46
  • @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 Dec 17 '22 at 15:14
  • @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 Dec 17 '22 at 15:55
  • I can't take a picture because I don't visit SE from a mobile. – Giovanni Dec 17 '22 at 15:57
  • @Giovanni if you have a mobile or camera, you could transfer a photo to the PC you visit SE from? – JeopardyTempest Dec 18 '22 at 10:27
  • @JeopardyTempest Really, even if I don't have Windows on the mobile? – Giovanni Dec 18 '22 at 10:30
  • @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 Dec 18 '22 at 10:42
  • @JeopardyTempest I see. If I see such clouds again, I could make a photo. – Giovanni Dec 18 '22 at 16:19

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