Contrail shadows

[vogon13]

I don't know if a man made meteorlogical phenomona is a suitable topic here, but I have been fascinated with jet aircraft condensation trail shadows for many years. Here in the great midwest they are a frequent occurence and I see them often. As you approach one, especially one with a low ground speed, you don't even notice until you are almost in it. The view of a contrail backlighted by the sun can be quite spectacular. The depth of the shadow can be quite substantial too. Sometimes if I'm not in one, I can see one crossing a cloud, generated from a contrail even higher. Never really seen this mentioned anywhere. Can't say I've seen a good photo of one, either. I wonder if Saturn's outer ring strands when highly inclined to the sun generate similar shadows that could been seen from above Saturn's cloud deck. I'm aware Cassini has photographed the shadow projected on Saturn by the rings, but what would it look like to a human observer on Saturn?<br /><br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[newtonian]

vogon13- I have never seen one (a shadow - I have seen the trails, and they can be really interesting just after sunset when lit by the sun at their high altitude).<br /><br />Where did you see them from: on the ground or in flight?

 

[nacnud]

If you like contrails check out these wierd things.<br /><br />Morning Glory Cloud

 

[newtonian]

nacnud- Interesting cloud!<br /><br />Note there may be northern lights tonight from the solar storm.

 

[nacnud]

Cool, I'll have to go look but they would have to be strong to be visible here (54'N)

 

[newtonian]

nacnud- Yes, me too.<br /><br />I am way south - south Louisiana. <br /><br />But I did see them here in the extremely powerful solar storm - was it about 1 year ago /><br /><br />Anyway, I'm going offline to look at the lights.<br /><br />And also the currently airing Science channel special on Huygens, and other space programs in the current space week special at said channel.<br /><br />Happy viewing!

 

[newtonian]

Nothing on the norther horizon now.<br /><br />Now on the Science channel its an update on Hugens on Titan, and Cassini.<br /><br />At 3:00 CT, a special on the Mar's rovers.<br />At 4:00 CT, a 2005 special on Jupiter, what has been learned in the last 25 years.

 

[newtonian]

Vogon - I did respond to your post as best I could.<br /><br />Have you seen Noctilucent clouds?<br /><br />Have you seen the Northern lights?<br /><br />I have, and both are awesome, especially the latter - best seen up north- I saw many displays in Alaska and Yukon.

 

[igorsboss]

<font color="blue">Cross-Posted:</font>font color=yellow>Has any one ever encountered the shadow of a jet contrail?<br /><br />Yes, and it was amazing, because I looked UP into the shadow! <br /><br />The key to my experience was the thick haze in the air at the time. The sunlight was diminished by the haze enough so I could look up near the sun fairly comfortably. <br /><br />You've all had experience with seeing a sunbeam going through a dusty room. Well, what I saw was the opposite of that... A shadow going through a hazy sky. <br /><br />Usually, we see shadows on the ground. In this case, I saw the contrail shadow darkening the sky above me. I saw an incredibly flat 2-Dimensional plane of dark sky edge-on. <br /><br />As I figure it, the contrail's width must have subtended between 30 minutes and 1 degree of arc. The effect was similar to being in a total solar eclipse, but where the sun was eclipsed by a line, forming a plane of darkness in the hazy sky above me. Wow.

 

[vogon13]

igorsboss and others:<br /><br />Your description of seeing the shadow plane extending from the ground up into the sky is exactly right. It is a remarkable experience that apparently happens all the time, and hardly anybody ever notices. I usually see the shadows while driving south on a N/S aligned interstate (most good contrails run E/W here). Plunging my brave little car through the shadow structure is a real hoot. ( I do advise caution while observing these from a car, you don't want to have an accident and be forced to explain what you were doing). These things can have incredible gound speeds or be almost stationary, interesting probe of wind speed at altitude. I saw a shadow once from an aircraft, but relative velocity made event very brief. On same flight , while aircraft banked, could see our contrail shadow racing along ground. Saw several simultaneously at sunset one day while with a group of people. I was the only one to comprehend what was going on. Also, at another sunset, think I saw one projected upwards onto lower(!) surface of cloud deck above me. Very, very weird. I hope somebody out there is more into these things than I am, I do not want to be the 'guru' of this phenomenon.<br /><br /><br /><br />Oh my! What great buys!<br />Nancy <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vogon13]

Hey, just remembered, I attempted to see if full moon could generate same (but dimmer) effect once but couldn't really see anything special. Suspect my pupils would have to dilate out to about 1 inch to get enough photons for this to be visible at night.<br /><br /><br /><br />Shop the great, warm indoors. Who do you know wants to buy a car?<br />Ernie von Schledorn <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[igorsboss]

Since the Sun (apparently) moves across the sky from East to West, shadows of contrails which also run East-West should be easier to observe.<br /><br />For contrails which run North-South, the Sun's motion would cause the contrail shadow to move very rapidly from West to East, even if the contrail itself had zero ground speed.<br /><br />Hmmm... That's an interesting geometry question... For a stationary contrail at 33,000 feet above the ground, how fast does it's shadow advance across the ground? I've insufficient time to work it right now...

 

[vogon13]

Damn that's a weird cloud. All we get around here are tornadoes.<br /><br /><br /><br />What if there was no such thing as a hypothetical question? <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vogon13]

Speed of shadow shift per degree of apparent solar motion an angle that had escaped me. Most contrails here are commercial aviation and run E/W. Presumably most N/S contrails here are military. Those seem to be rather rare. Best contrail shadows from straight contrail across hole sky with consistent .5 to 1 degree apparent dispersion. Not sure a photo would do justice to this, probably a video would be better, but should be careful about pointing cam at sun. Would love to experience two of these at same time that were parallel to each other and observe from between both. <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[glutomoto]

I know nothing, but i found pictures.<br /><br />Earth Science Picture of the Day<br /><br />Wired News: Hot on the Contrails of Weather<br /><br />APOD: Contrial Clutter over Georgia<br /><br />APOD: Not really a contrail shadow but i had to include it<br /><br /><br /><img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[glutomoto]

Re: the shadow plane extending from the ground up into the sky...<br /><br />one more picture<br /><br />Contrail Shadow<br /><br /><img src="/images/icons/smile.gif" /> <div class="Discussion_UserSignature"> </div>

 

[vogon13]

Siberia picture very similar to what I saw from aircraft. No snow that day so did not see bright spot effect. Would a lake of liquid water have done that?<br /><br />Shuttle picture is stunning! HEY! EVERYBODY, GO LOOK AT THAT PIX!!!! Absolutely had not considered near vertical contrail from shuttle at sunset. Amazing depth of shadow. Usually see these things around local solar noon and contrast tends to wash out due to scattered light from dust in air. Really appreciate your post of that amazing picture! <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[vogon13]

And, just found 'classic' contrail shadow picture you posted. That is indeed what I experience. I wondered if pix could do justice to what I've seen and except for the motion derived aspect of 'plunging' through one, that picture captures very nicely what one of these contrail shadows looks like. Brightness of contrail itself and depth of shadow very good in photo. THANX THANX THANX!!! <br /><br /><br /><br />Thank you everyone, you've all done very well!<br />Mr. Grace <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[igorsboss]

I believe that ground-level haze is one of the key elements needed to see visible contrail shadows. So, if you go hunting for these, don't do it on a crystal-clear day.<br /><br />Smog as art.

 

[vogon13]

[bump]<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[lukman]

Why Vogon13 is not galaxies? who had turned Vogon13 into rock and dust? <div class="Discussion_UserSignature"> </div>

 

[vogon13]

This is an old thread. Back from a time when I had not yet earned my Galaxy rank.<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>

 

[MeteorWayne]

Technically vogons turn planets into rock and dust, but that's another show. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

 

[lukman]

Can he make me (comet) into a Quasar? <img src="/images/icons/tongue.gif" /> <div class="Discussion_UserSignature"> </div>

 

[vogon13]

I can turn you into pate . . . <br /><br /><br /> <div class="Discussion_UserSignature"> <p><font color="#ff0000"><strong>TPTB went to Dallas and all I got was Plucked !!</strong></font></p><p><font color="#339966"><strong>So many people, so few recipes !!</strong></font></p><p><font color="#0000ff"><strong>Let's clean up this stinkhole !!</strong></font> </p> </div>