Went went a bit further. Well, Went went a lot further. He suggested that the dark and foreboding clouds about to discharge on passing golfers are dark and foreboding because of the biogenic hydrocarbons that brought the charge when incorporated in the clouds.
Are black clouds due to hydrocarbons? Boulder-dash! Poppy-cock! No way José! News flash -- Went went bonkers! Went who? National Academy member recognized for his discovery ofauxinsin 1928. Well, Went is dead so I will have to be bonkers for him.
Foreboding dark clouds due to hydrocarbons? Where would he get such a notion? Frits cultivated a relationship with corporate folks at Pan American Airways and persuaded them to pass along to him the air intake filters from all the flights.
The black on the filters were a gooey mixture of hydrocarbons. Slimy black is then off to coloring some clouds. What! Black is a great color. What happens to all that hydrocarbon? Went went further and proposed that the hydrocarbons are rained-out and accumulate over the eons as petroleum deposits. It may have been other academy members who noted Went and disabused him of his petroleum theory.
So clouds are white except when they are not.
In my travels over the tropical ocean blue, the cumulus clouds at distance were brilliant white. Well, there are sort of gray or silver on the bottom of the cloud and on the side away from the sun (your run-of-the-mill silver lining).
My travels over the grass oceans of the West and Midwest imprinted the specter of dark and foreboding cumulus clouds.
From my porch in Virginia, with very few cumulus clouds from the ocean direction, my clouds are on the black side even on the side with the sun shining on it! Next year, I will become a serious watcher of clouds to expand my observational base. For now I can hit the books!
The best book for this kind of stuff is M. Minnaert's The Nature of Light & Color in the Open Air. With a title like that it must be a book of some antiquity. Right on. 1954. My copy is a Dover (love that publisher) reprinting the English translation from the 1930s original French edition. The book informs and entertains you on mirages, haloes, shadows, double rainbows and hundreds of other things you may see in the open air with the naked eye.
I can relate the flavor of the book to you with a couple of his topic sentences:
The beam of a searchlight furnishes matter for various interesting observations
It is worth while during a shower to observe in which direction the falling rain is most easily seen.
Now that is the stuff of a real selling card. Get your Dover catalog and outfit your bookshelf with a copy of Minnaert's little gem.
Minnaert has a nice section on "The Colour of Clouds." He begins,
It is a pleasure to watch the beautiful summery cumulus clouds drifting past, and to try to account for the fact that certain parts are light and others darker.
Just what we need. He notes that the drops in the cloud backscatter the light in the direction of the sun and so the bottom of the clouds and the side away from the sun are in the shadow of the cloud-drops above. He notes that this helps in the explanation a lot but doesn't explain all the differences in cloud color or colour.
Get this one.
If, when the weather is clearing up after a storm, only a few small cumuli are left, brilliantly illuminated by the sun, with no possibility of one casting its shadow on another, they grow darker and darker and finally blue-black when they are about to disappear.
Wow, that is heavy. He doesn't have an explanation for this little observation. But, he concludes by saying that we must consider the "possibility of there containing dark dust-particles as well.
Dirty clouds! Maybe Went's hydrocarbons in the air are still on the table.
Minnaert pleads with the reader to investigate why rain-clouds are so gray and thunder clouds so leaden in color. He worries that it is in dust. Dirty clouds. Well, it is still the meteorologists’ dirty little secret that nobody seems to know for sure.
Well, we are left with more questions than answers this time. Here are some rules of thumb that you need to keep in mind. Thunder and lightning storms are most common in maritime tropical air and over land with a high primary productivity! Out West, cool marine air comes ashore on its way east. Lightning is not common over the coast range; it is more common over the Cascades; and, it is more common still by the time it reaches the Rockies. Are the plants loading it up with charge and hydrocarbons, and condensation nuclei, and/or ice nuclei, and after sufficient accumulation lightning bolts and rain plummets rain down!
Be honest. You've seen black snowflakes falling, right? You also know that, in my quest to understand the atmosphere in terms of the biosphere, I have implicated the kind of ice nuclei produced by decomposing vegetation in the kinds of flakes you are likely to get. Unfortunately, black snowflakes are not flakes made dirty by biogenic hydrocarbons. You see black snowflakes against a gray sky. Black, gray and white differ in their brightness, for which the surrounding background provides the standard of comparison. When the snow is falling, the flakes have less light on them than the cloud does from the sun atop. The sky is brighter than the flakes below and so the flakes appear gray or even black. We can attribute this explanation to Aristotle.
Let me try. A white snowflake falling against a black surface really looks white. The same flake seen against a very white background will be seen as black. The same flake seen against different backgrounds appears different. Telephone wire seen against a bright sky will look dark while seen against darker sky will seem white. Black is a great color but so too is white. There is a lot of stuff that is degrees of blackness and or whiteness. It is all about brightness and contrasts.