21 January 2015

Contrails and Distrails

Posted by Dan Satterfield

Image by Joseph Mandeville.

Image by Joseph Mandeville.

Florida meteorologist Chris Smith received the picture above from viewer Joseph Mandeville today wanting to know what caused this. It’s a DISTRAIL. The cloud was made up of liquid cloud droplets that were well below freezing (supercooled water is common in the atmosphere), and when an aircraft flies through it the tiny soot particles can act as condensation nuclei and cause the liquid water to freeze. The ice crystals fall out, and leave the clear slot. Just the disturbance in the air can do it.They are seen on satellite images as well from time to time.

While we are on the subject of white lines in the sky… Steve Brown at KSAT in San Antonio,Texas tried to talk reason to some of his local chemmies. It does not do any good but I give him an E for effort! It’s actually worth doing, because it cuts down on the numbers who fall for this silliness.

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