Are some clouds actually inherently darker than others?

Factual Questions
1

A number of times (like today) I’ve looked at the sky and noticed that some clouds look much darker than their neighbors. Possible reasons why that might be the case:

  1. The bright ones are in direct sunshine, the dark ones aren’t;

  2. I’m getting fooled by the kind of optical illusion seen here; or

  3. They really are darker, perhaps because they hold more moisture/per unit of volume, maybe due to differences in altitude or such which affects ability to hold moisture.

Today tho it would appear to me that the clouds in question were right next to each other, in the middle of the day (sun high in the sky), tho to be sure there was an altostratus/cirrostratus layer behind (and above) both. But what do I know.

2

I think it’s mainly number 3.

3

And pressure. I was watching tornadoes form during a particularly bad storm and the clouds would appear instantly in the funnel from changes in pressure.

If you look at a storm front that backs into another the compressed high-pressure area can be a very dark color.

4

I’m interested to hear the answer to this as well. My instinct is to say that darker clouds are either denser (3) or are in the shadow of other clouds (1), but by whatever reason simply do not reflect and/or conduct as much light through their structure as lighter clouds.

N.b.: I have never seen dark-colored cirrus clouds.

5

This is right, if you’ve ever been in the plains, you can see a rainstorm from certain angles, depending on the light.

This is right as well, the darkness of a cloud can be as allusive a chasing your shadow.

Finally, you aren’t entirely wrong here either, but I but put it more like, only thunder clouds are actually that much more inherently darker than another cloud.

If I’m way wrong here, I’d also like to know . . .

6

Since you asked:

I’m pretty sure you meant elusive.

:slight_smile:

7

It’s often scuds, those very low and slowly drifting irregularly shaped ones, which often appear to be darker than those in the background or even middle ground. I saw a number of those today.

8

Thanks, I saw that but didn’t have to time to edit.

It could make sense though, if you meant to allude to the act of chasing your shadow? :dubious:

9

What about the amount of dust the water droplets condense on? Does that make any difference?

10

Cirrus clouds are ice crystals at altitude. The moisture level isn’t dense enough form thick clouds.

11

Ok. Let’s look at it this way. Clouds are mixtures of air, solids, (like dust), ice, water, and vapor. Some clouds are purely water, does that mean they have more particles to settle on? Could be sure, but those specks are just those, specks.

We know how light works with dust, we’ve all seen a glowing column of particles in the air, brilliantly illuminated. So now we just imagine somehow some water evaporated and a cloud forms around these particles. Are they brighter? Does the water just hang on them where they are, or when at it’s most cloud like, does it spread the particles around, according to its preference.

I’d like to say yeah, it plays a pretty big part in the reflection or absorption of light. But there is some debate on whether particles really have much effect on a cloud at all, or just kind of get stuck and hang their. Sure, it could help the cloud seem to shine brightly, but either water or dust will appear bright in enough light, so how do they work together?

12

I’m going to try and take another shot at explaining the practical implications of what makes clouds dark or “bright.”

Go to a nightclub and watch the lights blast over the fog from a fog machine. This isn’t like a cloud at all, just vaporizing water mixed with glycol or glycerin, or simply mineral oil. This is such a cool effect. Now carefully note what would happen if you saw columns interposed in the light, or rather the layer principle. One fog machine close to you, one fog machine at the other end of the room. Now if you see some colored light sweep by past the second fog, is the thickness bearing on how much light gets through?

So the “shadows” of other clouds, or simply seeing one cloud behind another, and the sun penetrating as much as it can, you obviously can’t see as much sunlight in the come past the thicker areas.

How much stuff is in a cloud would only help it along somewhat, considering the weather is mild. If there are more vapor and particle specks wouldn’t the cloud be brighter? Think about it, more surfaces for the light to bounce off of. This is why on normal, too cloudy days, they all have about equal opportunity to become bright, if they are under direct sunlight.

It matters little what’s all in a cloud, as I’ve hypothesized before. You can find this out by filling an enclosed space with steam, and then smoke (which is particles) and playing with a flashlight or bright light source.

On an overcast day, or simply in a localized storm, the pressure and whatnot keeps all the moisture and other “puff” that’s up there, highly charged and seemingly thicker. If you took a safe airplane ride past the accumulation, you could see sun shining on the other side of the clouds, though.

So essentially I would sum it up like this. The atmosphere is full of this massive system that makes up the clouds, which is like a sponge and whirlwind tunnel, with little holes for rain and circulation, some areas rather dense and some not. The sun can either “glow” up a cloud like a lave lamp, see the orange and pink clouds in sunsets? They are very bright. Or the sun sometimes can’t pass through at all, simply by so much activity in the clouds, they are busy making crashing into each other and making storms. Or sometimes on moderate days, the sun has distributed power to make all seem relatively balanced.