Cloud of the Week #9 : Cumulonimbus

It's easy to see why Cumulonimbus are called the King of Clouds.

Cloud lovers, this week we are going to tackle a progression of cloud forms in the cumulus genus. I think you are ready to observe some of the subtle differences that distinguish one type from the next. So let's start with a cloud that's been visiting our early spring landscape here in South Puget Sound--the cumulonimbus. This cloud is also known as the thunderstorm cloud or the "thunderhead." For those of you cloudspotters who are also wine lovers (me! me!), the cumulonimbus is the meteorological equivalent of a bold zinfandel, whereas our earlier delicate cirrus species are on par with a pinot noir.    The bases of these convective clouds can extend from 2000 feet above the ground to 60,000 feet or so--which means their tops are reaching the tropopause (the boundary of the troposphere where it meets the stratosphere). In 1896, this cloud genus was classified as cloud nine in the International Cloud Atlas as it was the highest cloud (cloud one being the lowly stratus). Being "on cloud nine" came to describe a state of great elation among us land-bound humans. The expression still has currency today despite the little-known fact that subsequent reclassification pegs the cumulonimbus at Cloud Ten.

This is not a cumulonimbus cloud, it is a cumulus congestus. You can tell because it has the tight, cauliflower-like shape.

  

  You can watch a cumulonimbus form in a matter of minutes. Keep your eye on the rapidly rising clouds that seem to be churning out their outer edges--a cloud that resembles the one pictured above. This is a cumulus congestus cloud. It is composed of water droplets and due to the convection within the cloud, it is growing rapidly and rising toward the top of the troposphere. And, because pressure and temperature generally decrease with elevation/altitude, the water droplets in this cloud will start to freeze as they continue to rise. As the water droplets become ice crystals, the well-defined edges of the cloud soften. Now this cloud, pictured below,  is classsified as a cumulus calvus. Calvus means "bald," which will make more sense in a minute.

This is a cumulonimbus--a species called calvus. The cloud has lost its sharp edges.

This is a cumulonimbus cloud--a type called capillatus. The lower "fringe" of this cloud is precipitation--rain or  hail.

 Now, our cloud is a full-fledged cumulonimbus capillatus as its top loses all definition as the ice-crystals increase and give the cloud a fibrous or wispy, hair-like appearance at its edges (in contrast to bald, or calvus). Capillatus means "hair like" in Latin. (Trick for remember this: capellini is angel hair pasta.).  Not only does our cloud get hairier, it flattens out as it reaches the upper boundary of the troposphere. This boundary, called the tropopause, limits the clouds growth. As our cloud flattens out, it becomes a tri-nomial: cumulonimbus capillatus incus. The word "incus" indicates is has the flat, anvil-shaped top.



This might be your view from beneath a cumulonimbus cloud.

   And because the clouds have been puring themselves down on us this past week, let's clear up nasty rumor about raindrops: they are not tear shaped. Small raindrops are actually spherical, like a ball.  This is because a sphere is the shape that requires the least amount of energy for the drop to hold itself together.

   As drops grow bigger than a millimeter or so, they start to become flat along their bottom edge as they fall, due to the resistance of air flowing around the drop. By the time a drop reaches 2-3 mm in diameter, it looks more like a hamburger bun than a sphere.  Drops bigger than about 6 mm in diameter are relatively rare because the air resistance tends to cause the drops to breakup as they fall.  

  And speaking of big raindrops, the largest one ever observed was 8.8 mm (possibly even 1 cm!). This Guinness Book of Record holders was measured by UW scientists Art Rangno and Peter Hobbs over the Amazon Basin and Marshall Islands in 2004.



Big, hamburger-bun-shaped raindrops require big umbrellas.



Fog Lark News

Downy Marbled Murrelet on its tree-top nest. Actually this is the preserved form of the chick discovered on its nest in 1974 in a Douglas-fir in Big Basin Redwood State Park in California. The discovery was made not by a birder or ornithologist, but by a tree trimmer working in the 220-foot-high fir. When this chick pecked at his vicious speed saw, the tree trimmer decided the bird was worth saving. The bird is now in the collection of the California Academy of Sciences.  

  I've been writing about clouds almost exclusively the past few months, but it's time to hark back to the subject of my last book,Rare Bird. The bird is the marbled murrelet, an endangered seabird that nests in the old-growth coniferous forests of the Pacific Coast. Early loggers called it a "fog lark," because they would hear it's call early in the mornings when the thick coastal fog obscured all but the lower trunks of the trees they were felling. Few loggers likely ever saw a murrelet as these birds are secretive and camouflaged in the forest and silent on their elusive nests.

  You can see photos of the murrelet and read more about this amazing bird on my website .

  If you're in the Puget Sound region, I'll be giving two talks about this bird. One (a very brief introduction) for the Olympia Mountaineers Wednesday, March 2, at 6 p.m. And on March 9 for the Seattle chapter of the Sierra Club at the REI. 

The cover of Joan Dunning's new book shows an adult murrelet and it's chick on a moss-covered branch, likely hundreds of feet up an old-growth redwood tree. The nesting location of this unusual bird wasn't discovered until 1974.

  Though my head is in the clouds these days, working onStill Life with Clouds, author-illustrator Joan Dunning, has created a beautiful children's book on the marbled murrelet. It's calledSeabird in the Forest and it's due out in April from Houghton-Mifflin. Click here for a sneak preview of the book. Joan has published several books for adults and children on natural history topics, including Leaving Home, Secrets of the Nest, and From the Redwood Forest . She lives in Arcata, California enviably close to the marbled murrelets. Through her art and writing, Joan has worked passionately to help conserve the old-growth forests and it's mysteries. The story of the murrelet chick is a compelling one that will appeal to adults and children alike.

Thoughts on Cloud Collecting

    I have been reading a marvelous story of Luke Howard, the man who gave the clouds their names in 1802. The story is told by Richard Hamblyn in The Invention of Clouds: How an Amateur Meteorologist Forged the Language of the Skies.   
    In the second chapter of this book, “A Brief History of Clouds,” Hamblyn discusses the development of  a branch of meteorology called “nephrology”—the study of clouds—which began in Greece in the 6^th and 7^th century B.C. Back then, scientists were philosophers, mathematicians, and astronomers and were interested in theories on the composition of the universe (earth, water, fire, air in various combinations and proportions), how the earth was held afloat (on an aqueous bed), and what exactly clouds were (vapors of melted snow carried aloft by summer winds). In 340 BC, Aristotle put forth his ideas on clouds in his treatise, Meteorologica, which emphasized the role of the four essential elements (earth, air, fire, and water) and their associated paired qualities (heat and cold, dryness and moisture) in nature. The clouds were simply exhalations of the warm and moist elements of the physical earth; the exhalations mingled into various cloud forms in a layer halfway between the earth and the heavens.

     The Greeks “had not meteorological instruments with which to confirm or refute their observations of nature,” writes Hamblyn, “but in a sense this hardy mattered as their genius lay more in the questions they asked than in any of the answers they hazarded.”

   Aristotle’s theory dominated nephrology for two thousand years, until, ultimately, 17^th-century philosopher, Renee Descartes deduced that the clouds were “most likely water droplets or small particles of ice formed by compressed vapours given off my objects on the ground, rather than my Aristotle’s mingled ‘exhalations.’” I have not read enough of Descartes to know how he arrived at this conclusion, but it is amazing that he arrived at it at all given that, even when armed with an extra four centuries of knowledge and technology, most of us would falter when asked to explain (well) what a cloud is.

    Hamblyn puts Descartes theory in historical context:

   “The span of Descarte’s life had see the six instruments introduced which would determine the future direction of all scientific investigation: Following the appearance of the telescope, the microscope, the air pump, the pendulum clock, the thermometer, all in the first half of the seventeenth century, scientific inquiry would never be the same again. Shared methodologies, whether in the field, the laboratory or the private museum, would arise as the mans to apprehend the teeming world of things. Meteorology shared in this gathering sense of advance and, in concert with the rise of other kids of measurers and compilers, the era of the weather collector had begun.”

      I was about to get hung up on Descartes, when I got hung up on the word “collector” instead. I don’t like the word. I’ve never been a collector of things, but lately—thanks to the pocket-size digital camera I have—become a collector of images of clouds. Thousands of them. Every time I leave the house for a walk  or to drive somewhere, I talk my camera “just in case” I see a beautiful, interesting, or unusual cloud. This, by the way, is all of them.

   The photographs are either on a card in my camera, somewhere in Adobe Photoshop, or in various folders labeled Stratus, Cumulus, Cirrus, Mixed, UFO. Most are in the UFO file. I have too many photographs to identify and sort. But I can’t delete them. I need them, all of them, not just the good ones. 

   So what’s the problem? At least I’m not using film, paper, and toxic chemicals to develop them, right?

   Right. The problem is that once I take a photograph—once I hear the shutter click—I stop looking at the cloud. What’s worse is, I also stop seeing it.

   Here’s the typical sequence: 1) While searching the sky for an beautiful/interesting/unusual cloud, I spot one, 2) I pull out my camera and photograph it, 3) I put my camera away and walk on because, 4) I feel I have “acquired” the cloud and the ability to look at it later, identify it, categorize it, post it on my blog.

       “Quickly we stick labels on all that is, labels that stick once and for all. By these labels we recognize everything but no longer see anything.” This from a book called The Zen of Seeing, by Frederick Franck.

 Alaskan writer/photographer Kim Heacox tells a story in The Only Kayak of throwing his very nice camera into Glacier Bay when he realized that it was an impediment to his relationship with the wilderness and to really seeing what was in front of him. As long as he toting a camera and collecting images, he wasn’t purely being in the wilderness, seeing it purely with his own eyes. Kim eventually replaced his camera and has since made himself quite a reputation as a wilderness photographer. I imagine the act of drowning his camera had something to do with developing his keen eye.

   Collecting is funny business. Animals collect and store food as a survival strategy, but we collect as a hobby. Trinkets and things stores want you to buy in multiples are called “collectibles.” (Gee, isn’t pretty much anything collectible?) Yes! I have the official  Cloud Collector’s Handbook—a handy book of photographs of major and minor clouds by type with points assigned to each type based on its rarity. A common stratocumulus earns 10 points, an altocumulus lenticularis (the UFO cloud) 45 points. Published by the Cloud Appreciation Society, the slightly tongue-in-cheek book works the way a Life List does for birders, allowing the use put check marks (but no points) beside the observed bird. Collecting names, lists, and even photographs of birds gained and continues to gain popularity when collecting birds (aka shooting or trapping) was dooming them (the great auk, Carolina parakeet, ivory-billed woodpecker, and passenger pigeon to name a few).  But cloud collecting? 

      The point of the book is to get people to look up, see the clouds, and have some fun trying to learn what type they are. "You don’t have to own something to collect it," writes the book's author, Gavin Pretor-Pinney, "You don’t even have to hold it. You just have to notice it and record it." This is admirable in this age of consumption, though you do need to buy the book to be able to collect the clouds. I just hope the collectors remember to keep looking up after they check off the clouds and tally up their points.

Photo courtesy Saophlkun Ponlu and Creative Commons

     A few Sundays back, I read an article called “Fun Stuff: Why pictures of object collections are popular now” in the New York Times.  Apparently, the American consumer’s attitude toward “stuff” is subtly shifting. People aren’t so interesting in buying stuff, but in seeing online images of stuff—“lovely photographs of carefully arranged groups of objects.” You know, groups of scissors, pine cones, measuring cups, sewing bobbins, baseball bats—all artfully arranged and photographed and posted online. What’s going on here?

  Rob Walker, the author of this article and seven years’ worth of other ones appearing weekly in the “Consumed” column, says these images are merely modern still lifes. What these online virtual collectors are doing with scissors and measuring cups, early painters of still lifes were doing with fruit, flowers, goblets, freshly killed rabbits, fish, and fowl. The various objects were assembled, carefully juxtaposed, and, by the artist’s skillful brush, turned into a still life that promised to be more than a sum of its parts. As museum goers, we stand before the work of a 17th-century Dutch Master, marveling at the detail all the while looking for something else in the painting.  

   The still life, Walker writes, is a “genre whose attraction…has less to do with documentation than with capturing a way of seeing.

    And then he brings in a poet for the clincher. The poet is Mark Doty, author of Still Life with Oysters and Lemon, in which he observes that still lifes capture “A faith that if we look and look we will be surprised and we will be rewarded.”

   And that, I realize, is exactly what I am doing. Except that I am the still one and am looking and looking at the restless clouds for something surprising and rewarding. And if I am still enough for long enough, and if don’t reach for my camera, and because I am not looking to gather information as Aristotle and Descartes were, that something surprising and rewarding is often a message to let go.

   Let go of the stuff, let go of the images of the stuff, let go of the camera, the jpgs, the categorizing, the binomial labels. Just watch the cloud, see the cloud alone with your eyes.    

Cloud of the Week #8: Cumulus Fractus

 

   This week's cloud is a happy, low-level cloud called cumulus fractus--relatively small, ragged-edged clouds that seem more like mist than a cloud. The "fractus" part of its name is from the Latin for "part" or "fraction." These clouds typically form as detached cloud at 2,000-3,000 feet above the ground and are scattered across the sky in a somewhat haphazard fashion.
   Cumulus fractus form in two ways: They can form  in fair weather as rising pockets of warm air rise and condense into these proto-clouds that may develop into larger cumulus clouds with more defined "cauliflower" like edges. As cumulus fractus make their way across the sky, the moist air in them tends to evaporate in the surrounding dry air--so they don't stick around long. Below, you can see the deterioration of one cloud over just a few minutes.

This is a cumulus fractus cloud at its most compact stage.

Same cloud, seconds later, beginning to break up on the "top" side.

A few more seconds later it is really losing its form as it evaporates in the surrounding air.

Cumulus fractus may "grow" into larger, more defined cumulus humilis clouds like these.

     You'll see cumulus fractus on not-so-fair days, too, as they "shedded" by larger cumulonimbus cloud after a rain storm (see dark cloud below).

   One of the essential qualities of clouds is that they are always in transition, always on their way to becoming something else, never holding the moment too tightly. Cumulus fractus clouds are a great way to start watching clouds because their you can witness their constantly changing forms as they hurry across they sky. More distant clouds, such as the cirrus "Clouds of the Week," actually move faster, but because of they are miles above us, their changes appear to be taking place more slowly and more subtly.