November 2016

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A Mystery in the Clouds

Earlier this month, a peculiar ring appeared in the clouds over Warwickshire, England. James Tromans, who photographed the formation, asked what might have caused it. Clearly, this was time for some cloud detective work.[/vc_column_text][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” text_align=”left” css_animation=””][vc_column][vc_column_text]The ring was actually more of a curve, or a ‘U’, as there was no other half to it. It appeared to consist of regular lumps, or lobes, hanging down from the underside of a cloud layer. We wondered if this layer was an Altostratus, but off in the distance to the right of the image there appeared to be showers, like those produced by a storm cloud. This suggested that the cloud layer might in fact have been part of the huge canopy that spreads out at the top of a Cumulonimbus storm cloud.[/vc_column_text][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” text_align=”left” css_animation=””][vc_column width=”2/3″][vc_column_text]Sometimes, to the rear of a storm, lobes of cloud known as mamma can be seen hanging from the underside of the canopy (see image 1). There certainly was a general appearance of mamma in the cloud layer. But could some of these mamma cloud lobes have arranged themselves into this strange, regular curved formation? It seemed unlikely.

There was something decidedly unnatural about the cloud’s appearance – as if it were man-made. Then it occurred to us that the photograph was looking towards Coventry Airport. Might this cloud effect have been in some way caused by an aircraft?[/vc_column_text][/vc_column][vc_column width=”1/3″][vc_single_image image=”80708″ img_size=”large” add_caption=”yes” alignment=”center” onclick=”custom_link” img_link_target=”_blank” qode_css_animation=”” link=”/gallery/photo/photo-n-3241-2″][vc_empty_space height=”15px”][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” text_align=”left” css_animation=””][vc_column width=”2/3″][vc_column_text]As planes fly through clouds made of ‘supercooled’ water droplets, they can encourage these extremely cold droplets to freeze and fall below, leaving behind a gap, known  as a dissipation trail, or ‘distrail’. Such formations are often seen in straight lines where planes ascend or descend through the cloud. But they can also appear in circular shapes when one is flying in a holding pattern as it waits to land (see image 2). James’s cloud wasn’t quite a distrail, but we felt we were getting close.

It was then that we recognised the regular spacing of the lobes. These sometimes appear below aircraft condensation trails (see image 3). They are caused by the interaction between the two swirling vortices produced by the wings. As these rotate in opposite directions in the wake of an aircraft, the two turbulent flows interact and combine to form a periodic pattern of turbulent downdrafts. In the right conditions, they appear as lobes hanging below the condensation trail.[/vc_column_text][/vc_column][vc_column width=”1/3″][vc_single_image image=”181592″ img_size=”large” add_caption=”yes” alignment=”center” onclick=”img_link_large” img_link_target=”_blank” qode_css_animation=””][vc_empty_space height=”15px”][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” text_align=”left” css_animation=””][vc_column][vc_single_image image=”181600″ img_size=”large” add_caption=”yes” alignment=”center” onclick=”custom_link” img_link_target=”_blank” qode_css_animation=”” link=”/gallery/photo/photo-n-3798-x-2/”][vc_empty_space height=”15px”][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” text_align=”left” css_animation=””][vc_column][vc_column_text]This explained the formation. It was caused by an aircraft, which happened to be flying just above the base of the cloud layer as it turned in a holding patternabove the nearby airport. The plane’s condensation trail was hidden within the cloud layer, but the lobes of cloud descending below it, caused by the turbulence from its wings, appeared extending below the layer.

Phew! With that cleared up, we could finally relax once more.

Turbulence lobes beneath the contrail of an aircraft in holding pattern over Hampton Lucy, Warwickshire, UK, by James Tromans.[/vc_column_text][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” text_align=”left” css_animation=””][vc_column][vc_separator type=”normal” border_style=””][vc_empty_space height=”15px”][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” text_align=”left” css_animation=””][vc_column][vc_column_text css=”.vc_custom_1473510756057{background-color: #ffffff !important;}”]

A Response from our Poet in Residence

[/vc_column_text][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” text_align=”left” css_animation=””][vc_column width=”1/2″][vc_column_text]kt-thumbnailKatharine Towers, poet in residence at the Cloud Appreciation Society, has written the third of her Cloud Studies inspired by our Clouds of the Month. Here is her commentary on it:

It was quite a challenge to write a poem about a condensation trail! I was keen to avoid getting involved with the technicalities of ice droplets and downdrafts, as such poems can easily be side-tracked into just showcasing unusual vocabulary.

What eventually seemed interesting was the idea that we can’t help trying to interpret natural phenomena – or seeing things we don’t understand in terms of things we can describe. The use of the word ‘U-turn’ in connection with the unusual circular contrail gave me a way into the poem.[/vc_column_text][vc_empty_space height=”25px”][/vc_column][vc_column width=”1/2″][vc_column_text css=”.vc_custom_1479937854022{padding-top: 25px !important;padding-right: 25px !important;padding-bottom: 25px !important;padding-left: 25px !important;background-color: #ececec !important;}”]

Cloud Study III


A long-drawn breath that won’t last
or an after-thought spelled out
in ice and heat and fall-streaks

or that hush that follows pain;
what’s left when everything has been said.

Hard to believe they mean nothing –
yes, even this one
shaped like a change of heart.

© Katharine Towers, September 2016[/vc_column_text][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” text_align=”left” css_animation=””][vc_column width=”1/2″][/vc_column][vc_column width=”1/2″][/vc_column][/vc_row][vc_row row_type=”row” use_row_as_full_screen_section=”no” type=”full_width” text_align=”left” css_animation=””][/vc_row]

21 thoughts on “November 2016”

  1. Alyson Purling avatar Alyson says:

    Great detective work, I really enjoyed the trail. Thanks guys. Alyson

  2. Yes, Anne.
    Katharine has been our new poet in residence for a few months now. She has been writing wonderful poems, which we plan to publish at the end of the year of her residency. You can see her two previous poems for the recent Cloud of the Months here:
    We are very lucky to have her contributing!

  3. Anne Stevenson avatar Anne Stevenson says:

    I didn’t realize we have a Poet in Residence!

    And what a lovely poem, thank you, Katherine.

  4. Peter Evans avatar Peter Evans says:

    The cloud and it’s detection is fascinating but well done to Katherine for a super poem!

  5. Peter Roper avatar Mr Peter Roper says:

    In my humble opinion the three smaller “objects’ are nothing more than specks of dirt/dust on the camera sensor. The larger black object is certainly a bird flying at no more than 150ft. unless James’s camera is very dirty!

  6. Nicholas Ireland avatar Nicholas Ireland says:

    Writing as a pilot I can confirm that the “Winglets” fitted to many modern aircraft are designed to reduce wingtip vortices and thus reduce drag and improve fuel efficiency. However, aircraft flying at that height do not generate condensation trails and a holding pattern is flown a a racetrack pattern with two parallel straight legs of one minute duration and two 180 degree turns, also each timed to take one minute, giving a for minute pattern

  7. Nigel Cook avatar Nigel Cook says:

    I thought the new wingtips on modern aircraft reduced this turbulance, aka as in bird flight where is was taken from.

  8. Mary J Craig avatar Mary J says:

    Now that you all have the formation of the clouds and birds sorted out, let’s hear it for a very fine poem by Katherine – kudos to you, dear! Nicely phrased! ??

  9. Laurence Green avatar Laurence Green says:

    “Fait accompli”


  10. Photo Editor avatar Photo Editor says:

    Have added an image to Mikes forum post, may solve another mystery…IanL..

  11. Laurence Green avatar Laurence Green says:

    Most helicopters have a tell-tale”tadpole” shape to them. The object in the topmost part of the photo has all the hallmarks of a “tadpole” shape.

    Fascinating the way this intriguing photo has provoked welcome discussion. Keep it coming.

    As an aside, I think maybe the famous Belgian detective, Hercules Poirot, (author – Agatha Christie) might be called in to investigate further. Hmmm….!


  12. Elizabeth Berlangieri avatar Elizabeth Berlangieri says:

    Well if it’s not a bird or a plane…maybe it’s Superman?

  13. Christine von Allwoerden avatar Christine von Allwoerden says:

    Most fascinating pic and explanation by Gavin and others. Not sure if I can make out a helicopter..

  14. Laurence Green avatar Laurence Green says:

    The two birds in the lower part of the picture are minute compared to the big heavy “object” way, way above which would be even smaller given the vast height difference. Two birds cannot generate themselves generate enough energy to work onto the cloud, either from above or from below.


  15. Dick Holman avatar Dick says:

    Is James Tromans in the forum? I’d like to know if he saw a helicopter or a bird. I think it’s a corvid, perhaps a rook or a crow, and it has three companions in the background, unless James’ lens was mucky. :)
    Superb photo, definitely worthy of being Photo of the Month.

  16. Laurence Green avatar Laurence Green says:

    Hi Gavin

    As an ornithologist I can certainly vouch for the silhouette as definitely not being a crow. The “wings”, in relation to the elongated heavy body, are far too short. The silhouette, given its size in relation to the cloud and ground ,would translate to a really huge, huge bird of Condor size.

    Crows have large “flappy” wings and short bodies. They are big heavy birds (highly intelligent at that) so they maximise their precious energy when flying by proceeding dead straight with no wavering on their onward path. That is why the old English saying comes about:- “To fly straight as a crow”. Also, crows do not fly that high up – to do so would serve no purpose and cost them dearly for energy spent. They are not a bird of prey, they are carrion feeders and that means easy food pickings, especially where human beings are about and discarding easy-to-get food etc.

    I am an aviation enthusiast of some 5o years plus. I know aircraft and helicopters like the back of my hand. This is definitely a helicopter. The silhouette is really high up in the sky. At that height, as said, the “crow” or any other bird would be of huge size.

    Fascinating the correspondence this marvellous photo has provoked. Love it!


  17. Laurence, do you mean that little black shape near the top, to the left of centre? I’m pretty sure it’s a crow!
    Michael, that’s a great follow-up with your post in the Forum. As you suggest, it does indeed look just like a crowd watching a bonfire:

  18. Michael Lerch avatar Michael says:

    Fascinating! I will post in the forum a recent photo of an unaware recording of such an occurrence . I wonder, Boeing has developed and installed a new wing tip ” wing” that is supposed to get a bit more fuel efficiency for the aircraft. Are these vortexes produced by the new wing tip or are they a sign of the unimproved ?

  19. Laurence Green avatar Laurence Green says:

    I think the answer lies in the silhouette of the “aircraft” – it is a helicopter. The stubby sponsors on the craft are not the large slender wings as evinced on a passenger etc aircraft. Maybe if it were hovering over the same spot for some time the powerful downdraft of the helicopter’s rotor blades may have caused this peculiar cloud formation to occur.


  20. Laurence Green avatar Laurence Green says:

    Detective “Dick Barton” – Special Agent – has certainly been working overtime solving this intriguing mystery.

    Well done. I am sure other CAS members will be fascinated by the information provided.

    Glad to see it was chosen as “Cloud Of The Month”. So it should rightly be deemed thus.


  21. Hans Stocker avatar Hans says:

    Congratulations James and detectives. Mystery solved. Great picture and great explanation. I now know the origin of the lobes you can often see under contrails.

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