1. Marin B

    Marin B Active Member

    I was looking at yesterday's timelapse video (24 hr in 2 minutes) taken from the Berkeley hills looking west to the Golden Gate Bridge. At 1min, 12 seconds, a cloud starts to form just right of center, and it forms into a long contrail-esque cloud, that passes out of view at 1 min, 15 seconds. From the way it appears in the timelapse, it doesn't look to me like it was caused by a plane. But, it also doesn't look natural. What do you think? (see attached file -hopefully it's in a viewable format).

    [​IMG]

    [​IMG]

    https://www.metabunk.org/attachments/sfbay_23feb16-avi.17657/
     

    Attached Files:

    Last edited by a moderator: Feb 24, 2016
  2. Mick West

    Mick West Administrator Staff Member

    I think it's a contrail that starts out too faint to be really visible. It's also possible it interacts with a cloud layer, kind of like making a long fallstreak.
     
  3. Marin B

    Marin B Active Member

    Seeing the segment looped the way you have it makes it look more evident to me that it's a contrail. Given the timing, my guess is that it was right about 3pm, which is around the time we routinely get LAX-bound jets from Asia flying over the bay area.
     
  4. skephu

    skephu Senior Member

    I looked at flightradar24 playbacks but no plane fits the bill. All fly well below contrail altitudes.
     
  5. Mick West

    Mick West Administrator Staff Member

    I suspect something like this (or the following planes)
    [​IMG]
     
  6. Trailspotter

    Trailspotter Senior Member

    I think it was a natural linear cloud. There was one in the Aqua satellite image taken on February 23, 2016 around 22:00 UTC (2 PM PST):
    [​IMG]
    It has a correct orientation and tapered end and by 3 PM it would be brought to about right distance from SF/Berkeley by a high altitude westerly wind with the windspeed of 105 km/h (70 mph).

    This cloud reminded me about an unusual linear cloud that I saw the last Summer:
    https://www.metabunk.org/striped-linear-cloud-over-norfolk-england-kelvin-helmgoltz-cloud.t6755/
     
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  7. Trailspotter

    Trailspotter Senior Member

    I've modelled the location and orientation of the linear cloud on Google Earth using its photo from another thread:
    SF Halo GE.
    This photo was taken shortly before it was posted on Facebook at 2:54 PM EST. Viewed from Berkeley Hill, the same model (purple line) placed at altitude of 10,000 meters (33,000 ft) runs parallel to the linear cloud in the time lapse video:
    Berkeley Hill GE.
    The model line is approximately parallel to the linear clouds in the Aqua photo in the previous post, but is about 100-110 km (70 miles) closer to SF:
    SF Linear Cloud GE.
    The camera icons mark the camera location of the above photos.
     
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  8. Marin B

    Marin B Active Member

    It's funny how you can observe something for the first time, and then suddenly you start seeing it everywhere. Today I spotted a "linear cloud", which before yesterday I had never heard of. I suppose had I seen this in the sky before yesterday I would have just automatically assumed it was a contrail. I guess February is a good month for skywatching in the SF bay area :)


    skinnycloud.JPG
     
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