Dragogoalie From Australia, joined Oct 2001, 1220 posts, RR: 7 Reply 1, posted (11 years 6 months 11 hours ago) and read 884 times:
"Many people are familiar with the long streaks of white clouds produced by jets flying at high altitudes. The clouds which are made up of condensed vapor called condensation trails, or contrails, are generally produced by jets flying between 25,000 and 40,000 feet in moist air. If the relative humidity is low, contrails may evaporate rather quickly, however, in high relative humidity conditions, contrails may remain visible for several hours. This indication of moisture content may point to other clouds and, possibly, precipitation moving into the area within the next day or two" (Jeppesen Private Pilot Manual p 6-26)
here you go, hope that helps. They also have a diagram showing that most of the contrail (if not all of it) is actualy made up of ice crystals, not water vapor.
Positive rate From Australia, joined Sep 2001, 2143 posts, RR: 1 Reply 2, posted (11 years 6 months 10 hours ago) and read 879 times:
On some really moist days the contrails are really long and defined and they can remain for up to 30 mins if the conditions are right. Sometimes a contrail will even dissipate and form a Cirrus cloud- quite amazing really!
Twotterwrench From , joined Dec 1969, posts, RR: Reply 5, posted (11 years 5 months 4 weeks 1 day 15 hours ago) and read 775 times:
Of course, there is the "new" explanation for contrails precipitated by Art Bell and his crowd of "they're coming to take me away" and "the internet is used for government mind control" people who say contrails are actually "chemtrails" sprayed by the US govt for every conceivable purpose including weather control and mind control. Put that in your pipe and smoke it.
A contrail forms because one of the components of jet engine exhaust is water. Jet fuel is made of carbon and hydrogen. When jet fuel burns with oxygen, most of the exhaust consists of CO2 (carbon dioxide) and H2O (water). The water is generally an invisible vapor. When you exhale, your breath contains a great deal of invisible water vapor as well. You may have noticed that on certain days in the winter your breath will form a cloud of condensation when you exhale. In the summer, however, you don't see your breath. In the winter the moisture in your breath hits the cold air and condenses into visible water vapor. Cold air can hold a lot less moisture than warm air, so the moisure form a visible cloud when you exhale.
The same thing happens when a jet engine "exhales". If the temperature, winds and humidity in the upper atmosphere are right, long white contrails form when the moisture in the exhaust condenses forming those long white contrails.
CloudNine From United States of America, joined Apr 2001, 68 posts, RR: 0 Reply 9, posted (11 years 5 months 3 weeks 3 days 2 hours ago) and read 655 times:
I'm gonna go the the Art Bell view. I kinda get this "fuzzy/goofy" feeling a few hours after standing under 3 or 4 of those contrails. The government is up to something ?....!!!....? I just know it!.....Peace On Earth OOops,gotta go! just saw another flying sauc.......