1. PlainandTall

    PlainandTall New Member

    Hi! I'm new to this forum and am not gung-ho to jump on the chemtrail bandwagon... but I have seen a lot of strange things in the sky recently (I love clouds and photography and spend a lot of times outdoors) and I don't know if it's a matter of my own awareness becoming more focused- or if things really are "different" in the sky... but I'm seeing things I don't ever remember seeing as a kid (I'm 42) I am familiar with sun dogs (I see them regularly) and this cloud was nothing like that- although it did have a slight golden rainbow hue to it. This bugger was ABLAZE with light reflecting from the sun... the picture doesn't capture the level of intensity of the light throwing off this linear cloud- but I think you can see it reflected in the pond pretty well- and none of the other clouds or contrails in the sky were reacting the same way. These two attachments are from the same photo- one is just a detail of the other. I do have other photos, but this one captured it best.

    South East Indiana 4/27/2012

    Does anyone have any optical/weather explanation to put my mind at rest?

    Attached Files:

  2. Mick West

    Mick West Administrator Staff Member

    Excellent photos.

    It's a sun dog, or at least part of the 22 degree halo. Normally when you see a sun dog it's part of a larger area of cloud. What you have here is that one contrail being at the right altitude and with the right kind of ice crystals to create a sun dog.

    See here:

    http://www.atoptics.co.uk/halo/dogim0.htm

    Remember what you are seeing is only a small part of what would be a larger optical phenomena if the contrail cloud were only large enough to reveal it. Sun Dogs are always at the same position relative to the sun, so I can take this one:

    [​IMG]

    And overlay it on your image. You only see the portions of the sun dog that are revealed by the contrail:

    [​IMG]

    And here's an other way of looking at it. The entire sun dog, and your cloud alone in the correct position

    [​IMG]

    And then a full sun dog over your large photo
    [​IMG]
    Last edited: Nov 20, 2013
  3. Mick West

    Mick West Administrator Staff Member

    A bit more on why just that one trail is bright, and the other clouds are not.

    [ex=http://www.atoptics.co.uk/halo/dogfm.htm][​IMG]Sundogs, parhelia, are formed by plate crystals high in the cirrus clouds that occur world-wide. In cold climates the plates can also be in ground level as diamond dust.

    The plates drift and float gently downwards with their large hexagonal faces almost horizontal. Rays that eventually contribute their glint to a sundog enter a side face and leave through another inclined 60° to the first. The two refractions deviate the ray by 22° or more depending on the ray's initial angle of incidence when it enters the crystal. The condition where the internal ray crossing the crystal is parallel to an adjacent face gives the minimum deviation of about 22°.

    Red light is refracted less strongly than blue and the inner, sunward, edges of sundogs are therefore red hued.

    Rays passing through plates crystals in other ways form a variety of halos.

    When the sun is relatively high, rays cannot pass through the crystal unless they are channeled by being internally reflected from the upper and lower basal (large hexagonal) faces. The skewed angle of incidence also causes the ray deviation to increase and high sun sundogs are farther from the sun.

    Plate crystals rarely float exactly horizontal, they wobble and the wobble increases with crystal size. Wobbly plates produce tall sundogs and in the more extreme cases the distinction between a tall sundog and fragments of a 22° halo becomes somewhat arbitrary.[/ex]

    Basically you need the right kind of ice crystal, and you need stable air. The most likely explanation is that that contrail was at a different altitude to all the other visible clouds - in a location were the conditions were right for these stable hexagonal plate ice crystals. It's a lot brighter because it's the only cloud in the sky that is refracting light towards you, other than those around the sun.
    Last edited: Nov 20, 2013
  4. SR1419

    SR1419 Senior Member

    I agree- in PlainandTall's close up of the sundog, the cloud it is on appears to be lower than the rest of cirrus* - at least that is how it looks in the picture.

    To me, the presence of refractive phenomena- sun dogs, bows etc...indicates the presence of ice and/or water...

    Why some folks then attribute these things to some kind of chemical or whatever they believe to be in "chemtrails" doesn't seem to make logical sense.

    Can barium refract light into sun dogs?

    Great pictures PlainandTall- reminds me of this picture from 1983:

    http://www.1000plus.com/Imagic/8301sund.htm

    [​IMG]
    Last edited by a moderator: Nov 20, 2013
  5. Mick West

    Mick West Administrator Staff Member

    I think part of it comes from the common experience of iridescence as being a result of an oily sheen on water.

    Iridescence oil on water and iridescence in clouds come from radically different physical phenomena.

    Oil on water is iridescent because of interferences between the reflection of light from the surface of the oil, and the reflection of light from the surface of the water, a few wavelengths below it. It's the same with a soap bubble, it's the front and back of a very thin film.

    Iridescence in clouds is due to mei scattering. Different sized ice crystals scatter different wavelengths of light. It's diffraction.

    Then you also have Irisation

    Quite understandable almost nobody understands these distinctions, so they kind of lump them all together. Clouds look "oily", when they are just pure droplets (or crystals) of water.
  6. PlainandTall

    PlainandTall New Member

    Wow Mick- That is an excellent explanation- thatk you so much for taking the time to break it down for me and also doing the photo overlays- I guess part of what threw me is that I expect sundogs to be level with the sun and this one seemed lower- but the fact that I was only seeing a little lower slice of the dog because only the contrail was there to catch it- so cool! I'm glad to know this picture is of a beautiful special phenemon I happened to catch and not something to have nightmares about!
  7. PlainandTall

    PlainandTall New Member

    IMAG0464.jpg

    This is the first picture I took of it- just with my phone's camera- it didn't get the same detail as the Rebel- but it did capture the INTENSITY of the light.
  8. Mick West

    Mick West Administrator Staff Member

    Last edited: Nov 20, 2013

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