Make your own free website on

May 28, 2000

(Page 3 of 10)

dashs2.JPG (12808 bytes)

Image #1

Image of a "dash-dash" contrail.

Answer: According to M. Kim Johnson, Physicist (""),  "If the atmospheric water content is not consistent with altitude (picture atmospheric "waves" of high water vapor content below a layer of low water vapor content much like
waves on the ocean), then a jet will alternately pass through
air that allows contrail formation and air that does not. This
gives the appearance of a dashed line if the plane is flying at,
or near the perpendicular to the waves."

dashs2big.jpg (18584 bytes)

Image #2

Enlargement of Image #1 of "dash-dash" contrail

I watched this contrail being formed and video taped the event.  At the time I believed the airplane was intentionally turning the contrail on and off but later, through study and careful observation, understood the dynamics causing this phenomenon to occur.  I have also watched straight-line contrails form then parts of that contrail dissipate until all that is left is a "dash-dash" contrail.  

There are actually people running around pointing to these two types of contrail phenomena claiming "dash-dash" contrails are caused by pilots turning some biochemical "spray" off and on.  I have personally observed and video taped/photographed both kinds of "dash-dash" contrails as they formed and I know this effect is due to atmospheric variations and not some conspiracy to wipe us off the face of this planet.

2000 A. Hebert

All photographs, images and material presented on this page
are copyrighted material and may not be copied or printed without prior permission from A. Hebert.