reply to post by CREAM
...the ones I see are more like the second picture of the OPs post...
The second picture in the OP's post are ALSO contrails. They happen to be taken from a point on the ground where air traffic is passing overhead on
many different headings, as the air traffic travels between various widely separated departure and destination points!
Look at a map of the United States, or Europe....look at airline schedules, and the city pairs that are served. You will see AMPLE spots where paths
cross, and airplanes flying those routes, when they make contrails, will leave them in a criss-cross looking manner.
image from 1967 happens to show an area where most flights were roughly parallel...that is the only difference. Could be
anywhere, but mostly on one of the Coasts (East Coast US especially, NorthEast sector) where there is so much traffic over the North Atlantic
routes...primarily west-to-east, and vice versa, of course. Even in 1967, VERY busy over those routes....today, more so....
Edit: Here's a link to an example North Atlantic Plotting Chart (most airlines use Jeppesen products, and they are seriously copyrighted...you have
to pay for the right to post them!)
Charts like this are used for navigation reference, and some simplified versions (the ones for actual "plotting") are used in flight, and written
on, as we track the over-water and out of radar portions of the flight, to verify navigational systems performance and accuracy. (These finished
materials are KEPT by the airline for a minimum of six months, in case any question arises later...like, they sit as "smoking gun" evidence if a
crew screws something up!).
Anyway, you may need help interpreting...but you can see all the points on the coast, both in North America, and in England/Europe where flights'
routings are "anchored", for the crossing over the Atlantic. Similar routes head down to South America, too...all over the World, there are
established waypoints like this, in the air, to navigate by.
The black triangles, those are the "intersections"/waypoints. "Intersections" are denoted by the five-letter 'names'. Other waypoints,
sometimes, by their Latitude/Longitude
(such as, "N49 W30" for cardinal coordinates in degrees...occasionally minutes will be used, if not on a whole degree point).
[edit on 29 June 2010 by weedwhacker]