Cloud of the Week #2: Cirrus vertebratus

Cirrus vertebratus           (photo by M. Ruth)
  May I present the Cloud for the (mid)Week. This is cirrus vertebratus, a type of cirrus cloud resembling a spinal column or fish skeleton, hence the Latin vertebratus for vertebrae-like. Like other cirrus clouds, this forms high in the atmosphere, usually starting out as a smooth band of ice crystals that is then blown by crosswinds to create the fine filaments or streaks to either side of the "column." This cloud, remarkably, features a spine attached to a cloud that resembles hip bones! FYI: I did not PhotoShop this image.
  These high clouds form at the same altitude as last week's cirrus radiatus--16,500-45,000 ft.--and usually indicate otherwise clear skies. They may however, thicken and begin a progression toward deteriorating weather.
  Many of you took my "Head in the Clouds Survey" last month and identified the jet contrails in one photograph as cirrus clouds. I should have given you half credit for this answer, because contrails and cirrus clouds both form at similar altitudes and do look alike sometimes . I guess you could call a contrail a faux cirrus or psuedo cirrus (which is more fun to say out loud).  Below is a photo of a jet contrail mimicking a cirrus vertebratus.

Jet contrail mimicking cirrus vertebratus   (photo by M. Ruth)

  In fact, this looks more like human vertebrae than the top photo. How do I know this is a jet contrail? Because I was watching the sky to the south of my home where I usually see jet contrails (heading north from Portland). I watched and photographed the deterioration of the contrail so I know this was not a naturally formed cirrus vertebratus. If such contrails formed amid authentic cirrus vertebratus, the identification would be trickier.
   Real Ci ve (the official code) materialize in the sky gradually, almost imperceptibly, are irregular in width, and do not have a plane at one end (!) Jet contrails usually appear in the same sector of the sky (relative to your nearest airport), usually follow similar flight paths (mostly parallel, but with some criss-crossing), and are similar in width.   
  Though I have taken thousands of photographs of clouds in the past year, I would like to lure my readers to other websites where you can see thousands more. Click here to go to Clouds Online, a fabulous easy-to-navigate cloud atlas.
 
Next up:  Tangled Cirrus

Cloud of the Week: Cirrus Radiatus

Cirrus Radiatus at White Pass, Washington on December 31
  As promised, I will be presenting a Cloud of the Week here for those who want to ace my next Cloud Survey. We will start at the top of the troposphere, with the highest of the clouds and work my way through the atmosphere layers toward the earth to the lowly fog.

Here is Eric Sloane's cloud map from his book Skies and the Artist

  Though there are three basic cloud forms (stratus, cumulus, and cirrus) and ten basic types (cumulonimbus, altostratus, etc), there are hundreds of named species and varieties of clouds--enough for years of weekly cloud postings. Clouds classification is similar to plant and animal classification, but is based on the height and appearance of the cloud, not its genes or whether or not it can produce fertile offspring. Unlike plants and animals, clouds are classified by genus, species, and variety.
   Our first Cloud of the Week comes from the genus cirrus: cirrus radiatus. Cirrus is a Latin word meaning "fiber" or "hair." In general, these clouds are delicate and wispy, not unlike strands or locks of hair. They are composed entirely of ice crystals (not water droplets) and occur at high altitudes--16,500-45,000 feet above the earth.
  Cirrus radiatus is one of five species and four varieties of cirrus distinguished by the appearance and orientation of their streaks. This cloud's streaks appear in bands, usually aligned with the wind, that seem to converge toward the horizon. In fact, they do not converge at all. These clouds are actually parallel to one another. It took me a very long time to see this and to override the illusion of convergence. My head still spins when looking at cirrus radiatus like those in the photo above.
   In this photo, you can see some tiny clumps within the streaks. These are the ice crystals that form the initial cloudlettes that are almost instantly blown about by the winds (fast winds of up to 180 m.p.h.) As the heavier-than-air ice crystals descend, they encounter slower winds and lag behind the initial clump. The lagging ice crystals create the classic cirrus streaks. These clouds are sometimes called "jet-stream cirrus" as they are caught up in the fast winds of the jet stream.
  Weatherwise:  In isolation, cirrus radiatus, indicate high atmospheric pressure and--because of the orientation of their streaks--the direction of the winds aloft. Wind direction is useful to know as it will help you know where your future weather is coming from. Being the Accidental Naturalist, I took the photo posted here while cross-country skiing at White Pass. I "accidentally" looked up from the trail and saw these clouds. I travel with a camera, but alas, not a compass. So I do not know which way the wind was blowing. Literally.
  
Want more? click here to see another wonderful photograph of cirrus radiatus from the Cloud Appreciation Society website. If you have time on your hands, find your way to their Cloud Gallery and enjoy 747 photographs of other kinds of cirrus clouds.

Next Week: Cloud #2--cirrus vertebratus, the spinal columns of the sky.




Head in the Clouds Survey Results

  Thanks to everyone who took the time to fill out the survey. I sent the survey to 45 people and, thanks to those of you who forwarded it, received 67 responses. Though the survey was anonymous, I can tell you that the respondents included kindergardeners through octagenarians, those with scientific backgrounds and without, those currently working in scientific fields and those writing novels of science fiction, those with large office windows and those without, outdoorsy types and indoorsy types--a mixed bag, in other words. The results were fascinating and often hilarious. Many respondents decided to cover up their ignorance humor. My kind of people!
  Please note, that two years ago, I couldn't name more than a few cloud types and could recognize but one (the "thunderheads.")  I thought I was among the ill-educated minority, but after analyzing the results of this survey, it turns out that I am among the ill-educated majority. This makes me happy because it means there is a huge potential market for my book on clouds.
  In addition to some interesting multiple-choice answers, I received quite a few wonderful stories about first memories of clouds and close-up experiences with clouds. Thank you to everyone who shared these.
   Thanks to the online polling site, Survey Monkey, I am able to post the results to most of the questions in easy-to-read charts. The open-ended questions, however, required interpretation and analysis of a different sort. I tried to be scientific, but couldn't always manage.
  NOTE: Starting on January 3, I will be posting a Cloud of the Week photograph on this blog for all you budding cloud spotters.  Happy Cloudy New Year!
  
Question 1: How many basic types of clouds are there?


  The answer I was looking for was three: the three basic types are stratus, cumulus, and cirrus. The names are based on Latin terms describing the cloud's general appearance: stratus=layer; cumulus=heap; cirrus=curl (as in wisp of hair).

  The results were interesting for a variety of reasons. Though I inadvertantly included the names of the three cloud types in Question 6--and many people pointed this out to me--my gaff did not seem to overly influence the results. Only 37% of you answered "three."  It seems that those of you who knew a little something about clouds (that is, that there are hundreds of types), might be the ones who answered that there are ten basic types: stratus, nimbostratus, stratocumulus, cumulus, cumolonimbus, altostratus, altocumulus, cirrus, cirrocumulus, cirrostratus. But, no one actually named all ten in Question 2, so I am thinking that ten was a good educated guess.
      If you answered "more than ten," you get partial credit: there are hundreds of types of clouds, but they are not considered "basic." Each of the ten cloud types (genera) come in species and varieties (like plants and animals). So, there is a type of cloud called an altocumulus stratiformis perlucidus undulatus radiatus, though most people would call it "an altocumulus" if they called it anything at all.
   The only totally wrong answer was "five." Those of you who said five were, admit it, just winging it.

QUESTION 2: How many of these cloud types can you name?

A whopping 30 respondents correctly named the three basic types--stratus, cumulus, and cirrus.  Many named several types instead of or in addition to these--cumulonimbus being most often named. The most types named by one person was 9. Many people made up names, some quite amusing. Here is a sampling:

flat ones
fluffy ones
long stringy ones
nebulous
cutaneous
strato-something
wispy and forboding
venticular
cumonubis
clouds that look like sharks
rain clouds
something starting with the letter N...
crap, okay, so I don't know many clouds....

Luckily, no one was being marked down for spelling: cumulous, cummoulous, cummulus. The correct spelling is cumulus.

Question 3. How often do you consciously look at or notice the clouds around you?

It warms my heart to know that I know no one who never looks at clouds. For those of you who answered  "rarely"--I will let you know when you can pre-order my book.


Question 4: Do you look at the clouds to help you predict the weather?

I am glad to know that the Weather Channel hasn't completely taken over our brains and connection to the living planet.  In the few years I have been studying clouds and learning to identify them, I've also been trying to understand which clouds mean high pressure and which mean low pressure, which indicate a cold front and which a warm front. I've been looking to the clouds for clues to the weather 24 or 36 hours up ahead. I can predict rain now based on presence of cirrostratus clouds and a ring around the sun. Reading the clouds is a great skill to acquire, especially if you spend time in boats, on mountains, or trying to impress people at cocktail parties. But here in the Pacific Northwest, saying "I knew it was going to rain" doesn't really impress anyone.


Question 5. Can you recall your first memory of watching clouds? 

This question split respondents almost down the middle--half being able to recall their first memory, half not.   The earliest memory was from age 3; the most common age for the first memory was 5.  The most common memories were of looking for shapes in the clouds (hippos, ducks, princesses, sailboats, dragons, animals, umbrellas were named) and of watching a "thunderheads"(cumulonimbus) of an impending storm.  

Nine described lying (sometimes laying) on their backs in their backyards, on their lawns, in hay fields, fields, or somewhere "outside" in the summer.
One person described lying outside and looking at the clouds to 'make them disappear.'
 One respondent said they were disappointed in the clouds that didn't resemble anything.
One person recalls being on a road trip as a four year old and staring out the window watching the cloud after cloud after his/her father put a strip of duct tape down the middle of the back seat "as a demarcation line between my rival sibling and me." 
  My first memory was at the ripe age of 12, when I remember getting laughs for spotting clouds that looked like Richard Nixon in profile. This would have been 1972.


Question 6: What type of clouds are these?

                                         

The correct answer is cumulus. This is a type of cumulus cloud called cumulus humilis. These are low, puffy individual clouds composed of water droplets (instead of ice crystals) and are found at altitudes of 2,000-3,000 feet. The "humilis" part of its name means it has minimal vertical extent--a humble cloud. This type of cloud indicates fair weather, but can build into a cumulus mediocris, then a cumulus congestus, then the giant cumulonimbus under certain conditions.

Question 7: What type of clouds are these?



  Most respondents correctly identified these as cirrus clouds. They are the highest clouds, occuring at altitudes of 16,500-45,000 feet, and are composed of ice crystals (not water droplets). This type of cirrus are officially known as cirrus uncinus, which means the streaks are shaped like commas or hooks. When you see these clouds, watch for a deterioration in the weather. Often these cirrus will spread, thicken, lower, becoming altostratus clouds (a mid-level layer) and then nimbostratus (a low-level rain-bearing layer).   Several of you chose "other" as your answer to this question and provided some nicknames for these clouds:
   mare's tails [an accepted nickname] 
   the long stringy ones [hmmmm..]
   long-haired democrats fleeing the party
   chiropractors


Question 8:  Everyone loves pink clouds, but can you explain why they are pink? 

About two-thirds of the respondents had a basic grasp of this phenomenon, using words such as "reflection,"  "refraction," "sun," in their answers. A subset of this group managed to include words such as "atmosphere," "angle of sun," "dust particles," "penetrate," and "wavelength." But because I included my large, extended family of liberal arts majors and my friends in this survey group, I suspect many of these responses do not actually reflect any real comprehension of the phenomenon.

Several (as in seven) respondents offered an explanation that indicated a comprehension of the phenomenon...and a willingness to put it down in writing. Before I offer the real explanation, I would like to share some of the less scientific explanations:

something with reflection and light and something i don't know
because everyone looks good in pink, even men...
sunset?
sailor's delight?
bending light into lower wavelengths
I always think of a newborn baby's blanket
they're embarrassed
a storm is coming
it has to do with the time of day
can't explain it, but feel like I have known
because the sky is on fire with my wittiness?
to make us feel nice at the end of the day?
rho scattering [this stumped me and ten pages of Google searches, then lead to a virus attack of my computer and much gnashing of teeth]

The short answer is: when the sun is low in the sky, the atmosphere scatters the short, blue-looking wavelengths of the sunlight and only the longer red- and orange-looking wavelengths penetrate the atmosphere and reach our eyes.  The scattering is a combination of refraction (bending), reflection (bouncing), and diffraction (more bending) of the light waves.

The long answer, complete with helpful analogy for sports lovers. NOTE: This explanation took me half a day to compose, with much gnashing of teeth because I realized I didn't fully understand the phenomenon adequately to be able to explain it to ya'll:

  The sunlight we see (visible radiation) includes light of differing wavelengths (imagine a rainbow or prism). From shortest to longest, the  wavelengths appear as violet, indigo, blue, green, yellow, orange, and red.  
  When these wavelengths enter the Earth's atmosphere, they collide with microscopic particles of dust, salt, soot, mist, aerosols, water (sometimes in the form of clouds). The collisions cause the wavelengths to change direction, bounce, and bend repeatedly due to what some of you referred to as  of reflection, refraction, and diffraction. Stay with me.
   During the day, when the sun angle is high, the wavelengths have less of this obstacle-laden atmosphere to penetrate. Sportfans: Think of the Earth as a baseball, with the layer of atmosphere being the leather cover. Imagine poking a set of pins of varying lengths (representing the wavelengths) straight down through the leather cover--easy, right?
  Now, in the early and late parts of the day, the sun's angle is lower and the wavelengths have to penetrate more of the atmosphere. This would be the equivalent of stabbing your pins nearly horizontally through the leather cover--not so easy, right? In fact, you are probably bleeding right now.
  Let's substitute your pins for light rays and the leather cover for the atmosphere. For most of the day, the shortest wavelengths--the violet- and indigo-looking ones--are scattered (which is why the sky isn't purplish). The blue-looking wavelengths are short, but long enough to penetrate the atmosphere and reach our eyes without being scattered by the particles of dust, soot, moisture, etc. This is why the sky appears blue most of the time. 
  At sunrise and sunset, however, when the sun angle is low, the thicker layer of atmosphere scatters the blue-looking rays, too, so they do not reach our eyes. The longer, red-looking wavelengths (your really big pins) are not scattered and travel unimpeded to our eyes--giving us pink sunrises and sunsets. 
   In the photo above of the pink clouds, the atmosphere is clear enough for the blue wavelengths to still penetrate, but the extra moisture in the clouds scatters all but the red- orange-colored wavelengths. Voila! A beautiful, cloudy sunset.
   I do hope this helped.

QUESTION 9: Have you ever experienced a cloud up-close--either by hiking to cloud-level in the mountains or at ground/sea level (fog)?
 Only two respondents answered "no" to this question. All the rest of you had great stories to share about flying through clouds or hiking through stratus (fog), nimbostratus (low rain clouds), or some higher cumulus clouds. Close-up encounters took place in a variety of locations--surf casting in Monterey Bay,  hiking in the Cascades, boating in Puget Sound, hunting in the Scottish Highlands, rowing on the Potomac River, walking to school in Port Angles, hiking in Glacier National Park, driving in Arkansas, standing atop the Empire State Building, hiking in Costa Rica and Anchorage and Huangshan "Yellow Mountain" in China.
 My favorite answers:
  "I was fascinated with being in a cloud...but disappointed when I found out that being in a cloud isn't anything like being in cotton candy or feathers or marshmallows or whatever else clouds look like." 
  "...we got very wet adn even though it wasn't raining, the fir trees were dripping water. It was like they were combing the moisture out of the cloud."
  "My first memory of being in a cloud was in the winter in a meadow and we were snowmobiling and we all stopped and wondered at its magnificence adn then drove through it which was very exciting and probably pretty stupid!"
 


Question 10 Can you identify these types of clouds? Do you know how they are formed? (The round thing is a moon, not a cloud).

  Short Answer: This is a contrail, short for condensation trail.  
 
    Of the 67 respondents, 10 answered "contrails" or "jet trails; "
    15 did not know or guess at the correct answer.
    A smattering of respondents anwered "stratus," "cirrus," "cumulus," "altocumulus," "smog," "jet stream" (which is not the same as the stream of exhaust from a jet).
    And....two smarty-pants identified the tree on the left as a Douglas-fir. It's a hemlock.
    And one respondent, unable to leave the answer blank, decided to provide information on how the moon was formed ("when an asteroid slammed into the earth and slammed a chunk loose. at least that's one theory i've heard.")
      
For those interested in more....   
Long Answer: A contrail is a long, narrow cloud produced by the exhaust of a jet engine. The engines emit hot, moist water vapor and particles of unburned fuel and soot. Most contrails form above 20,000 feet. Depending on the temperature and moisture in the surrounding air, the water vapor will condense in the cold air, form wataer droplets, then ice crystals, then a cloud. If the air is relatively warm and dry, the contrail will evaporate quickly; if the air is relatively cool and moist, the contrail may linger and grow in size. The contrails in my photo had been hanging out in the cool moist air and were expanding and being spread by the wind. These old contrails look different from straight and narrow newly formed contrails.
 
  NOTE: I didn't Photoshop this...but thanks to the respondent for the back-handed compliment.
  
  And because I just can't stop, below is a photo I took from my front yard of a distrail, short for dissipation trail. It's the inverse of a contrail. How these are formed will be discussed in an upcoming Cloud of the Week blog posting. 

Thrush music, hark!

   I was working at my kitchen table yesterday morning, reading some of what I have written about clouds over the past year, red pencil in hand. It was shortly before 8 o'clock. I noticed the light outside changing and stepped barefoot onto my back deck to take a good look at the sky (above). At this hour, with the near-solistice sun so low and muted, it was difficult to tell blue sky from gray cloud, white cloud from white sky. I couldn't discern what was in front of or behind what, what was solid what was space. There are maps like this where the shading along the borders between land and water are supposed to suggest three dimensionality, but somehow do the opposite so that Puget Sound or the Chesapeake Bay look like peninsulas.
   While I was out trying to make sense of what I was seeing, I heard what I thought was a Varied Thrush. It is a bird I first heard in California's redwood forests, before dawn, while I was searching for Marbled Murrelets. The thrush's song intrigued me; it sounded like a flying sauce taking off. It was buzzy, wobbly, and not melodic--so unlike the Wood Thrush that sung its graceful and liquid song in the Virginia woods behind my house. I have heard Varied Thrushes in late winter in our neighborhood in Olympia, though I have never laid my eyes one. 
    This morning, however, the bird seemed to be calling from my back yard. I ran on tiptoes inside to get my binoculars and, after a few buzzy calls, I saw a robin-sized bird in the top branches of the bare maple tree, it's golden breast catching the first light of the day. I would like to tell you it sang for me, but it didn't. It flew off--a dark silhouette against the eastern sky.
    I do not have the kind of camera that can capture a decent photograph of a bird unless it is sitting absolutely still and no more than four feet in front of me. But the Internet is full of wonderful, high-quality photographs of birds. This one (below) looks most like my Varied Thrush.  
Photo taken in Colville National Forest (copyright Lori Aull). Used with permission. Click here to see more of her work.