1. Rory

    Rory Active Member

  2. Spectrar Ghost

    Spectrar Ghost Senior Member

    Based on context I'd presume it's a reduction in surface temperature of 0.159C.
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  3. Graham2001

    Graham2001 Active Member

    A 1905 book on clouds has been uploaded to Project Gutenberg, the scans of the illustrations are not perfect, but the show quite clearly that clouds back then look like clouds now.

    Cloud Studies by Arthur W. Clayden (1905)


    The authors introduction recommends the book to meteorologists, artists and anyone who is interested in the sky.
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  4. SR1419

    SR1419 Senior Member

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  5. mikret

    mikret New Member

    can persist for hours - --
    I'm not sure that a few hours, but I'm sure that I watched 30-40 minutes ..
    everything depends on the weather and the airplane.
  6. Mick West

    Mick West Administrator Staff Member

    To see them persist for hours you usually have to look at satellite image, as the wind has generally carried them out of view after a couple of hours. They also spread out, and it's hard to distinguish them from other clouds.

    I think more commonly people see contrail cover that last hours, and don't realize it's from different contrails. Like:

    Source: https://www.youtube.com/watch?v=kQekGClN5GE
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