Color of Clouds: Dark Pink at Night, White in Morning?

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Discussion Overview

The discussion centers around the observed colors of clouds at different times of day, specifically the phenomenon of dark pink clouds at night compared to white clouds in the morning. Participants explore potential explanations for these color variations, considering factors such as scattering, light pollution, and local environmental conditions.

Discussion Character

  • Exploratory, Debate/contested, Conceptual clarification

Main Points Raised

  • Some participants suggest that the pink color of clouds at night may be due to light pollution from urban areas, particularly in metropolitan settings.
  • Others propose that the clouds reflect the colors of the sunset, especially if they are high enough to catch the light after the sun has set.
  • A participant mentions that the pink clouds observed are not related to sunset but occur during the monsoon season, raising questions about other illumination sources.
  • There is a suggestion that the color could be influenced by local environmental factors, such as dust or manufacturing pollutants.
  • One participant introduces the concept of nocto-luminescent clouds as a potential explanation for the observed colors.
  • Another participant references the saying about red skies and its relation to weather prediction, discussing the scattering of light and its effects on cloud color.
  • Some participants express uncertainty about the specific reasons for the pink color, indicating that it may be a combination of factors.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the reasons for the pink color of clouds at night. Multiple competing views and hypotheses are presented, with ongoing uncertainty about the underlying causes.

Contextual Notes

Participants note various assumptions and conditions, such as the influence of urban light sources, the timing of observations, and local environmental factors, which may affect the perceived color of clouds.

yash25
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Why is the color of the clouds dark pink in the night as compared to the black sky? Also..why is it white in the morning when the sky is blue..(is it because the cloud molecules scatter red wavelengths along with the blue ones? )
 
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I've never seen pink clouds at night, unless you're talking about immediately after the sun sets. In that case, the sun is below your horizon, but the clouds are high enough up that their horizon is farther away. They just reflect what you previously saw as a red sunset.
Remember that clouds are merely water droplets along with some impurities such as dust and airborne pollutants.
 
Oh no..im not talking about the time when the sun sets.. Actually it's the monsoon season here..and the rain clouds appear pink in color against the black sky late in the night much after the sun has set. so ...i don't really know what must be happening in this case?
 
If it is long after sunset, the only things that could illuminate the clouds is light from the ground or the moon.
 
The color of the clouds comes from scattering, and there are many, many relevant scattering processes that can occur depending on the relative positions of the sources (sun, 'light pollution'), the observer (you) and clouds; the composition of the clouds, the polarization dependence, etc. etc.

Here's a great site to surf around:

http://www.atoptics.co.uk/
 
wow..maybe it is light pollution ! because i live in a metropolis...
 
yash25 said:
wow..maybe it is light pollution ! because i live in a metropolis...

I live in Toronto, and the clouds here are yellow/orange at night due to the city lights. But your clouds are pink?
 
I don't know why the colour is pink? Maybe it's because of some other reason.And the colour is a dirty pink.Im from Mumbai...
 
Maybe there's a large red light district hidden in the middle of your city? :biggrin:
 
  • #10
If there's a lot of heavy manufacturing around, maybe iron dust is getting into the air?
 
  • #11
No...that can't be...because I'm staying in a residential area. Ald my house faces the sea. The clouds on top of the sea also are pink in colour! They're slightly dirty pink(pink mixed in murky black?)
 
  • #12
Speaking of sunset colours, can anyone tell me about the saying, "Red sky at night, shepherd's delight; red sky in the morning, shepherd's warning". I understand it is to do with predicting the weather. I do not know how accurate it is though.
 
  • #13
GrizzlyBat said:
Speaking of sunset colours, can anyone tell me about the saying, "Red sky at night, shepherd's delight; red sky in the morning, shepherd's warning". I understand it is to do with predicting the weather. I do not know how accurate it is though.

I donlt know about accuracy, but http://en.wikipedia.org/wiki/Weather_lore#Red_sky_at_night" regarding the rationale of the saying:

"Weather systems typically move from west to east, and red clouds result when the sun shines on their undersides at either sunrise or sunset. At these two times of day, the sun's light is passing at a very low angle through a great thickness of atmosphere, the result of which is the scattering out of most of the shorter wavelengths — the greens, blues, and violets — of the visible spectrum, and so sunlight is heavy at the red end of the spectrum. If the morning skies are red, it is because clear skies to the east permit the sun to light the undersides of moisture-bearing clouds coming in from the west. Conversely, in order to see red clouds in the evening, sunlight must have a clear path from the west in order to illuminate moisture-bearing clouds moving off to the east."

In a nutshell:
A red sky at night means the sky is clear to the West, where the sun is setting. That clear weather will be arriving in the morning.
A red sky in the morning means that clear weather that has passed over is now in the East, and the sun's red rays are now lighting up the incoming, wet clouds.
 
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  • #14
Maybe it is dust or a sand storm if you are in the middle east.
 
  • #15
If you're are saying that the clouds appear white during the day and the sky blue and that they clouds appear reddish and so does the sky at sunset then this is what everybody sees. Two words 'Rayleigh Scattering'.

http://en.wikipedia.org/wiki/Rayleigh_scattering
 
  • #16
maverick_starstrider said:
If you're are saying that the clouds ... appear reddish and so does the sky at sunset
He's not saying that. He addressed this very question in https://www.physicsforums.com/showpost.php?p=2252108&postcount=3":

im not talking about the time when the sun sets..
...the rain clouds appear pink in color against the black sky late in the night much after the sun has set.
 
Last edited by a moderator:
  • #17
yash25, Google nocto-luminescent clouds.

(Or variations such noctoluminescent, noctiluminescent, nocto-luminescent.)
 

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