We Murder to Dissect

     Clouds at Sunset in Virginia           Photo by T.Osowski

   A good friend sent me this photograph last week on his way home from work. I thanked him. I saved the photograph and set it as the desktop background on my computer screen. 

   I have been looking at this stunning picture every day and thinking I would try to figure out what was happening in that evening sky. My friend noted that the clouds were in front of high winds, forecast to be around 40 m.p.h. He did not identify the cloud types or suggest anything about a front, a low- or high-pressure system, or ask me to interpret or explain. He did tell me, however, that he pulled off the road to take this photograph.   That was all I needed to know about these clouds.

   Instead of consulting my cloud charts and meteorology textbook, I found my poetry book and "The Tables Turned" by William Wordsworth. Here is an excerpt: 

One impulse from a vernal wood
May teach you more of man,
Of moral evil and of good,
Than all the sages can.

 Sweet is the lore which Nature brings;
 Our meddling intellect
 Mis-shapes the beauteous forms of things:--
 We murder to dissect.

  Enough of Science and of Art;
  Close up those barren leaves;                               
  Come forth, and bring with you a heart
  That watches and receives.

To read the full poem, click here.

Fractus

  For those of you who enjoyed, were enlightened by, or read part of my previous blog How It Rains, I appreciate your dedicating a portion of your e-time to understanding this taken-for-granted atmospheric phenomenon. Sure, the Northern Lights are a much more spectacular-looking phenomenon, but I am not interested in sky bling right now. Drab, gray rain clouds are mind-bending enough.
   After I posted "How it Rains,"  I had quite a bit of clean up to do. I had markers, oil pastels, scraps of paper, pens, pencils, and other crafty things spread out all over my desk. I also had the remnants of the sponge I sacrificed in the name of science (above). The scraps (below) were too small to put to use in the kitchen, but I felt wasteful tossing them in the trash.

 So I decided to recycle them into my blog as an example of another cloud feature you should know about-- fractus. Fractus, as you can probably deduce, is from the same root as "fraction," meaning "part of." Cumulus fractus, therefore, are parts of cumulus clouds. Stratus fractus, parts of stratus clouds. These are the patches, misty bits, ragged edges, deteriorated fractions of larger clouds. You will see them floating by on their own or beneath a larger cloud mass. The free-floating ones are cumulus fractus and are often white.

The shreddy bits of white cloud are cumulus fractus.

 
 Unless the light is fading and they appear pink (below).

 Cumulus fractus in upper half of photo.        Photograph by M. Ruth

  Or gray after the sun has set (below).

    Gray Cumulus fractus just above trees.                       Photo by M. Ruth

   You might also see stratus fractus; these are gray.

If you see very dark gray stratus fractus beneath a nimbostratus cloud, they are called pannus (below).

How It Rains

 

A good day to contemplate the clouds. 

   I  woke up at 4 last Saturday morning and listened for a long while to the rain falling. It wasn’t a soft, gentle rain that might lull a person back to sleep. It was a hard, forceful rain that splattered on the hard, waxy leaves of the evergreen salal, rhododendron, and sword ferns out my bedroom window. It had been raining all night, on and off, mostly on. In fact, it had been raining on and off the previous day and the three days before that. This is to be expected in late February in the Pacific Northwest, especially after a spate of warm sunny days that false sense of spring that makes our hearts leap and crocus rise.

    I didn’t need another few hours of sleep on this particular Saturday morning, so I just listened to the rain and tried to imagine what was happening above the rain in the sky. What did the clouds look like that were bringing the rain? How low were they? Where were they coming from or going to?

   I pictured low, gray clouds—the nimbostratus clouds—moving in from the Pacific Ocean, over the Black Hills to my west, and down into our low-lying town of moss-covered roofs, gushing drainpipes, and soggy yards where miniature streams have meandered in from the street and braided their way across the lawn and flattened clumps of long winter grass.

  The rain had a pulsing rhythm so I imagined the clouds in bands—lower dark bands alternating with higher lighter bands. I had no idea how high, low, or wide the bands were, though I knew nimbostratus clouds could reach down to 2,000 feet and stretch across thousands of square miles of sky. From a satellite image, you might call them “extensive,” but on the ground, the word that most often comes to mind is “oppressive.” Especially in February, the month my mother and I called “Feb” because it sounded sodden and heavier, gloomier, and more oppressive than the lilting springing February.

  But I’m okay with Feb and its nimbostratus skies. It’s a good time to hunker down and wonder about such basic questions such as “how does rain rain?”

A completely inaccurate depiction of a rain cloud as a sponge.
(Original artwork by the Accidental Naturalist/Accidental Mixed-Media Artist). 

  Without thinking through the entire evaporation-condensation-precipitation cycle, it is easy to imagine a cloud like a sponge full of water squeezing out or shedding its contents and then moving on. This is understandable given the way clouds and rainfall are depicted on TV-news weather reports and in the newspaper—a sponge-shaped cloud with dash marks of rain falling from its base. But that puffy, scallop-edged cloud is not a rain cloud; it resembles most closely a type of cumulus cloud—a cumulus humilis. These clouds do not produce rain.

This is the underside of a cumulonimbus cloud. I know because I  got caught in it.  

  The two types of clouds that produce rain are cumulonimbus (the towering, convective clouds) and nimbostratus (the low, layered clouds). “Nimbus” means rain and these are the only two of the ten cloud types with this word in their name. Sometimes altostratus clouds produce rain—but it is a light rain, not sustained, and not what anyone where I live would call rain.

    "The Rain It Raineth,” wrote Veryln Klinkenborg in his New York Times column, “The Rural Life,” last November.  “It’s raining, I think, and then wonder what the “it” is that is doing the raining. Ordinarily, that’s just a linguistic question. But on a cold November day, it feels like a philosophical problem. It makes no sense to say the clouds are raining when the sky is so solidly, grayly felted.”  In this delightful seasonal musing from his farm in rural New York, Klinkenborg concludes that “what is raining is the rain, a phrase that sounds like the opening of a grim, Anglo-Saxon lyric.”

  He's right on both counts, but I would like to tell you how the rain rains and how a nimbostratus cloud allows this to happen.

  Nimbostratus clouds are deep clouds. From their bases at around 2,000 feet above the ground, they may extend as high as 18,000 feet. Nimbostratus are the "wet blanket" of the cloud world--a three-mile-thick wet blanket. So deep or thick are these clouds that they can hide well-developed cumulus clouds within them. 

    Like all clouds, nimbostratus clouds are composed of an unfathomable number of liquid water droplets, ice crystals, or both. For this blog posting, I am addressing nimbostratus clouds formed by liquid water droplets. 

   Recall that by the time we can see a cloud, the invisible water vapor in the air has condensed and grown into cloud droplets. The average cloud droplets measure about 20 microns in diameter, less than half the diameter of a dust speck, which, at 50 microns, is the size of the smallest object visible to the naked human eye.

This, dear readers, is a nimbostratus cloud as seen by the Accidental Naturalist equipped with a few blue markers.  My intent was to represent this cloud as a mass of drops and droplets in a complete and total frenzy within the cloud. (Please enlarge the image for better viewing.)

    Within our enormous nimbostratus cloud we have average-size cloud droplets, large cloud droplets (100 microns), and very large cloud droplets (200 microns), and many sizes in between. Within the cloud these droplets will move up and down, responding to both gravity (a constant force), to the natural updrafts within the cloud (a constant, but uneven force), and air resistance (which depends on the size and speed of the drop). During their life in the cloud, some droplets may evaporate and some may condense further and grow into raindrops. The raindrops are much larger than a cloud droplets, measuring from 1000 to 5000 microns. I have difficulty imagining 1000 or 5000 of anything, especially of something I have a hard time imagining--like a micron. So, in Accidental Naturalese, it takes a million cloud droplets to create a raindrop. Give or take.
   Now imagine zillions upon zillions of these cloud droplets and raindrops trapped within our nimbostratus cloud. They are all moving up and down within the cloud at different rates, letting gravity and updrafts have their way with them. Though many of the raindrops continue to grow through condensation, they are unable to grow large enough to overcome the updraft to escape the cloud as an earthbound raindrop. All these potential raindrops make for a very threatening cloud. So why doesn't it rain?

  Scientists have learned that no matter how much condensation a cloud droplet undergoes, the condensation process alone does not give us our rain. Condensation is a very slow process and meteorologist Donald C. Ahrens notes in his text, Meteorology Today, that it would take several days of condensation to create a raindrop from a cloud droplet. So what is going on here?

    Collision and coalescence. Wait wait...don't leave me! This gets fun. Plus, you've already done all the hard work of imagining a huge layer of cloud made up of zillions upon zillions (times ten to the zillionth) of unimaginably teeny and hyperactive drops and droplets of water.

A detail of the base of a nimbostratus cloud as envisioned by the Accidental Naturalist. Large cloud droplets at the base of the cloud are undergoing the collision-coalescence process.  (Please enlarge image for better viewing). 

       All those droplets and drops are not moving in unobstructed pathways within the cloud. The are colliding into one another. Think bumper cars at an amusement park and you have the idea. According to Ahrens, as the larger droplets fall faster than the smaller ones, they collide. Some of the smaller ones get caught on the forward end of the droplet, others are captured in the wake of the larger droplet and attach to the larger droplet's backside. The process of droplets getting caught or attaching to each other is coalescing.

The dark base of this cloud indicates that it is composed of very large raindrops.  Larger droplets  absorb more light than they scatter so I'd say it's time to grab your umbrella. 

     By colliding and coalescing, many raindrops are now large enough to get out of the cloud and find their way to your umbrella, your roof, your uncovered head. A very large droplet might take an hour to travel through a cloud.  Not all collisions end in permanent coalescence. Some collisions are so forceful that the raindrop smashes apart. Reduced in size, the drops and droplets may be again too small to overcome the cloud's updraft.While smaller raindrops are round, larger ones appear flattened (below left) due to increased air pressure against the bottom of the droplet. No raindrop is tear-shaped. Ever.

Large  raindrops (2-3 mm) are the shape of hamburger buns,  not the shape of a tear drop .

  What I have just explained about the life cycle of single drop or droplet of water in a nimbostratus probably took you less than five minutes to read. While you were reading there was a nimbostratus cloud floating somewhere over the earth. A cloud miles thick and thousands of square miles wide. A cloud composed entirely of drops and droplets in constant, frenzied, surging motion, up and down and up and down and finally down and out.
   With so many impossibly immense and infinitesimally small things to wrap our minds around at once, it is a wonder we can sleep at all.  

         

The Scale of the Universe

Please click here.

How High the Cloud?

My very own "glory." (All photos by The Accidental Naturalist.)

         Lucky, I got my window seat on a recent  Southwest flight to the East Coast. This time I was way forward of the wing in the bulk-head seats, which provide lots of leg room and no wing or engine to get in the way of my view of the clouds. It was an early morning flight and I sat on the left side of the plane. This was an unplanned but inspired choice because it meant I would be facing north, with the southern-arcing sun lighting up the clouds and landscape and casting the shadow of the plane onto the clouds.
    This meant that I had the possibility of photographing that optical, cloud-related phenomenon called a "glory." I wrote about this is a previous blog where you'll find the full explanation, a diagram, and a few photos that are not my own. I felt bad about the photos, but I never thought I'd capture one of these beauties myself. Now I have. Tip: If you fly eastward in the morning, sit on the left.

   I was fascinated by these clouds on our way into Chicago. They look like furrowed fields, but are clouds lined up in an undulating formation referred to as "cloud streets." The rows line up parallel to the wind and are created by spiraling air flow produced by a combination of convection and wind.
   I am 51 percent sure these are cumulus clouds, though higher altocumulus clouds also line themselves into neat rows like this. I tried to find a photograph of clouds similar to this one, but failed. So, how to make the call? I resort to some guess-timating based on altitude. Because I was taking these photographs, I knew we were above 10,000 feet. Why? At 10,000 feet, Southwest Airlines requires electronic devices to be turned off.
  Cumulus clouds typically form between 2,000-3,000 feet and I was definitely looking down on these clouds. But were they 8,000-9,000 feet below the plane? Hmmm. The other option was the higher altocumulus clouds, which typically form between 6,500 and 23,000 feet. Hmmm. These would be pretty low altocumulus clouds. I didn't see any clouds below these--an altitude-betraying cumulus, for instance.
   I was tempted to ask the stewardess to make an announcement: "Is there a meteorologist on the plane? We have an emergency."
   I kept taking photographs for a full hour after this photo above--and we were still looking down on these clouds as we descended into Midway Airport. I took this photo:  

   Help! Help! Help! Cumulus? Altocumulus? Something else? Stayed tuned.

Warm Sun, Icy Skies, Bittern

Cirrus duplicatus over Enumclaw, Washington

  Our recent and most-welcome warm weather in Western Washington this week has brought warm temperatures (50s F) and cloudy skies to the region. Cloudy?! locals might gasp. Yes, cloudy, the Accidental Naturalist insists. I'm on a mission to restore the good name of "cloudy" and divorce it from its knee-jerk association with low, gray, rain-making clouds. This weekend was cloudy. Just look.
   Saturday, my husband and I drove toward Enumclaw for a snow-free, low-elevation hike along the White River. With the dog. Who needed a leg-stretch. Who got us out on a rails-to-trails path outside the town of Buckley. Where we watched the skies get crazy with cirrus clouds that first caught my husband's eye because they looked "square."
   Nature isn't too fond of square shapes, especially in the cloud department, but these clouds had some edges and corners (at least from our perspective):

"Square" clouds indicate cirrus at more than one altitude with winds blowing the filaments in different directions.

  Once we started looking up at these clouds, we couldn't stop looking. Then the breeze kicked up. We walked a bit further, looking east, west, north, and south toward Mt. Rainier. We couldn't figure out what the skies were telling us. So I told my husband I thought the sky was "thickening" a bit and it would likely rain in 24 hours. Maybe 36. This was a mistake. I figured I had a 70-30 chance of being right. It was, after all, February in the Pacific Northwest. Often, cirrus clouds to portend rain. But only if they show a marked progression of lowering (to cirrostratus, altostratus, nimbostratus...rain). These cirrus dominated the sky.

I'm not sure what's going on here with this leaping cirrus cloud.

Here we have cirrus fibratus (I'm 86% sure) and what appears to be a salmonid migration of small altocumulus lenticularis.

  I have about fifty photographs of the skies on Saturday. I will spare you only so I have your attention for what happened on Sunday--another cloudy day in South Puget Sound. Look!

Clouds at sunset at Nisqually NWR. During the Super Bowl.  It is challenging to tell cirrocumulus from altocumulus--I haven't acquired the skill yet to judge the size of the cloudlets or height of the clouds. I'm working on it.

Heading west on the I-5 toward the Black Hills, the clouds produced a feature that looked like whale's baleen.  I believe these are trailing ice-crystals called virga. 

  At this point, you might be wondering why I seem to know so little about the clouds I saw this weekend. The problem is that despite my studying, constant use of cloud guides, sky guides, weather blogs, and National Weather Service data, it's difficult to match the clouds I'm seeing at any one moment to the data available. And no matter how many photographs I scrutinize, the clouds in the pictures (the supposed "type specimen") never quite match the pictures I've taken. Unlike the American Bittern.

An American Bittern, one of four seen hunting during the Super Bowl at Nisqually National Wildlife Refuge.

  Under those gorgeous sunset skies at Nisqually on Sunday, my husband and I were able to identify the secretive and camouflaged marsh bird--the American Bittern. This relative of the herons was hunting in the reeds and grass along one of the inner boardwalks. It looked just like its photograph in the Audubon field guide. We walked a bit further. And we saw four more bitterns. They looked and acted like the field guides said they would. It was so simple. And so satisfying.

The Water Cycle to the Rescue

Not your mother's water cycle.

   So there I was, trying to get a handle on The Water Cycle and its many graphic renditions when The Book Structure suddenly appeared. I had been standing in front of my laptop for a while now, messing with chapter files, cutting and pasting things, dragging files into folders, rearranging folders, and never feeling quite certain that all my notes on clouds would ever flow into a unified whole. 

    Over the weekend, I left the laptop behind, took up pencil and paper, and worked my many chapter headings into a new order. After three days, I had circled a lot of words and drawn a lot of arrows to move them up and down on the paper. 

   Because my book on clouds is not plot driven, I needed an overall structure that would allow me to get from A to Z gracefully. My book is a funny hybrid--that personal narrative non-fiction genre--that is not exactly a collection of essays, a thriller-paced adventure in the clouds story, or a look-what-I-saw-today-whilst-wandering-and-musing natural history. Organizing my book by the ten cloud types seemed forced as there are some cloud types (altostratus for example) that didn't beg for their own chapter. I thought about a four-season approach, but the clouds don't want to cooperate. I studied the tables of content of some of my favorite books on clouds and natural history to see what I could steal. Nothing made my fingers itch so I switched gears and ended up on the floor with all the books I could find that contained an illustration of the water cycle (below).    

But probably your mother's shag carpet.

    I sat in the middle of all of these books, ignoring my cup of coffee (upper right), the clock without batteries and my laptop which decided to hibernate, and my prize-winning terrain model of western Washington (all top). Because there were so many books, I had to lunge onto my knees to reach each one from my spot in the middle of the floor. It was sure easier on my back than sitting at a big table or standing at my laptop and, after a few hours of lunging and squatting and reaching and stretching, I realized I was kind of doing yoga. 

   The physical part of yoga (the postures) I am told, is intended to prepare your body for the mental part of yoga (the meditation). Move your body for an hour and you can more easily sit still for another hour. During the second hour you will more easily experience inner calm, an insight, or an epiphany. Here is what my epiphany looked like:  

Writing a book is child's play!  

  Maybe "epiphany" is too strong here. "Idea" is probably more suitable. What I had to say about clouds, it seemed, fell naturally into a pattern or structure that resembled a water cycle. I got out my scissors and tape and colored paper and chopped up my chapter titles, my list of themes, meteorological principles,cloud types, and geographic locations and then grouped them into the water cycle functions:  Evaporation, Transport, Condensation, Evapo-transpriation, Precipitation, and Run-off. I shuffled things around a bit and then taped all my pesky little pieces of color-coded paper onto large yellow cards. By the end of the day I had arranged these cards into a funky but functional water cycle. 

   I was feeling really good about my work until my 17-year-old son appeared in the doorway to my paper-strewn office and said without the least bit of curiosity, "What the hell, Mom?"

   I looked up, smiled proudly, and said, "It's my book."

       

The Water Cycle

Winner for most artistic and mist-like arrows. (Source: National Geographic Society, Exploring Your World)

   Certainly everyone remembers their very first Water Cycle poster from elementary school. Typically, the poster featured a body of water, a land mass, and some clouds with three wide curving arrows showing how water moves (evaporates) from the ocean or lake, becomes (condenses into) clouds, which then rain or snow (precipitate) onto the land and then flow underground and/or back into the ocean or lake. Three arrow--ocean, cloud, land--right?--kind of like the plastics recycling logo.
   I am sure many of you are nodding your heads, happy to have remembered this much. And, I am sure many of you are shaking your heads and saying, "Ah, if it were only that simple!"
   Yesterday, I went in search of the water cycle illustration. I pulled several books from my book shelf, flipped to the index looking for "water cycle" or "hydrologic cycle." The first one I found (above) is the work of Robert Hynes and comes from my go-to geography books published by the National Geographic Society in 1989. The illustration is beautiful, misty, round, and feels fluid like a water cycle. However, it includes not three arrows but five. Or maybe two. Some of them are double headers. Naturally, because this is a product of the NGS, all you need to know is packed into a text block/caption adjacent to the illustration.
   Before reading that text, I went to my next favorite book and found another lovely misty scene (below) and was surprised to see that there were seven arrows and they did not move in the continuous cycle imprinted in my mind from grade school. Huh! I grabbed another book.

Pretty darn artistic, but the labels kind of ruin the mood. (Source: Ahrens, Meteorology Today)

   That book was a college biology text book for a community-college class I signed up for fifteen years ago and then remembered I had two pre-schoolers at home and would have much homework, a lab, and an hour commute to the campus. I withdrew and kept the book--despite the fact that its water cycle looks more like a design for a water elevator (below). Rectilinearity aside, this illustration includes some enormous numbers--such as 425,000 cubic kilometers for the amount of water evaporated from the world oceans every year. Looking at water cycle maps without such numbers makes it easy to be lured into the notion that a big fat arrow is going to dump 425,000 cubic kilometers of water back on the earth. Do not be so lured. An estimated 385,000 cubic km of that evaporated ocean water falls as precipitation back into the ocean; and 111,000 cubic km falls onto land. That makes 496,000--not 425,000. The "extra" 71,000 cubic km of precipitation comes from evaporation from land plants (evapotranspiration).

(Source: Starr/Taggart, Biology: The Unity and Diversity of Life)

  I reached for my least popular cloud book, Cloud Physics: A Popular Introduction to Applied Meteorology, which included an illustration I mistook for a water cycle diagram (below). It is not, but you can see my confusion.

 A cascade impactor may move water, but it does not seem capable of producing clouds.  (Source: Battan: Cloud Physics)

   I almost missed this diagram (below) in my best-present-ever-from-my-husband-that-wasn't-butterfly-larvae book. The coastal landscape was unscenic, the clouds were not lovely, it was black-and-white, and the the cycle just didn't flow the way I wanted it to. This diagram resembles a cascade impactor (above).

(Source: Allaby, Encylopedia of Weather and Climate)

  A few books on my shelf are too smart for me. There were no color pictures in it. Nor were there any diagrams that represented the water cycle. I did wonder if this equation (below) might be the water cycle in code, but decided to turn the page.

Huh? (Source: McIntosh/Thom, Essentials of Meterology)

And I saw this: 

I really like this, but it is a diagram of the exchange of air in the troposphere. (Source:  ibid)

And then this: 

These caught my eye, but represent convergence, divergence, and vertical motion of something called "flow" I think that's air. (Source: ibid)

And then, from yet another book, this:

A little something from the HR Department? (Source: Barry/Chorley: Atmosphere, Weather & Climate)

  Lastly, in a most wonderful book, I found a water cycle lacking in artistry, color, and clouds (!) but one that depicts with elegant simplicity my local, Puget Sound water cycle (below). In fact, the vantage point of the reader, the Olympic Mountains are on left, Cascades on the right, and where I live, right in the center. And it has a dizzying array of arrows--about two dozen of them. This water cycle gets under my skin. In a good way.

Source: Kruckerberg, The Natural History of Puget Sound Country

  At this point, dear reader, you are probably wondering where I am going with all this. Perhaps you are dreading a somewhat longish explanation (in words) of the water cycle according the Accidental Naturalist. No, this would be too much at the end of an already longish posting.
   What I want to tell you is that after my unplanned and exciting foray into The Water Cycle, my arrow counting, my analysis of straight and curving lines, I seem to have discovered the perfect way to organize my book on clouds.
    More on that in my next posting.

Note: All photographs of illustrations from books paid for or borrowed by the Accidental Naturalist.