posted on Jun, 1 2004 @ 01:24 PM
Well, johnboy, there are certainly a large number of threads here devoted to the chemtrail issue. I don’t agree that there is something going on.
What you have observed are simply contrails. All aircraft engines produce two main exhaust compounds. CO2 and H2O. At typical flight altitudes,
the air temperature can be around -47 degrees F. That is pretty cold. As the hot moist exhaust exits the airplane engine it cools off rapidly and
the excess moisture “condenses” into ice crystals. At that point the ice crystals will behave exactly the same as a cloud formation at the same
altitude, since they are both made up of the same thing (ice).
At the temperature, and at the reduced air pressure at flight altitudes, a small amount of moisture in the air can make a huge difference in the
relative humidity (or more correctly the relative humidiy with respect to ice
If the RHi is low, then the ice crystals rapidly sublimate back into the atmosphere and you get a short lived contrail.
If the RHi is around 100%, you get a long lived (or persistent) contrail.
If the RHi is over 100%, then you get a persistent contrail that can initiate the formation of upper level cirrus clouds.
How can this happen? Air with a RHi over 100% is referred to as ”supersaturated.”
Generally at flight altitudes, the air can become
supersaturated because there is not a whole lot of particulate matter up there to initiate ice crystal formation. Airplane exhausts also include a
small amount of soot particles with the moisture.
The reason that you see more contrails in the daytime are probably based on a number of factors.
- increased air traffic during the day. More traffic = more contrails
- Maybe you haven’t noticed them as much because they are harder to see at night.
- Diurnal cycles in the atmosphere, including fluctuations in the barometric pressure, relative humidity etc. at flight altitudes. (to answer your
question) I believe that his phenomenon has been documented by meteorologists.
Two other things to keep in mind
- the volume of air traffic overhead has grown unbelievably over the past ten to fifteen years. More planes = more contrails.
- Modern jet engines are much more powerful and fuel efficient then they were a few years ago. This means that more of the fuel is converted to
exhaust gasses. Whereas before you had engines that produced a great deal of soot and smoke, and les water in the exhaust, the newer engines burn
fuel more completely, thus producing more water in the exhaust stream then before. More water = more contrails.
[Edited on 1-6-2004 by HowardRoark]