1 Steam Cars : Phorum
General Steam Car topics
Jet Vapor Trails
Posted by: John Butler (IP Logged)
Date: April 29, 2003 05:51PM
<HTML>Any one know what causes the vapor trail on a jet.? My friend and I are discussing what jets make them. My contention is that it is miliatary jets...causing the trail by the altitude they fly.....too high for commercial jets....she says its commercial.
any one know ?</HTML>
any one know ?</HTML>
Re: Jet Vapor Trails
Posted by: Peter Brow (IP Logged)
Date: April 30, 2003 02:02AM
<HTML>Hi John,
From what I've read, contrails are the condensation of water vapor in jet engine exhaust, occurring at the lower temperatures which are found at high altitudes. Burning hydrocarbon fuels creates CO2 from the carbon in the fuel, and H20 from the hydrogen. In warm air, water vapor in jet exhaust dissipates before it cools from superheated (invisible) to saturated (visible). Contrails are condensation (con) trails.
Peter</HTML>
From what I've read, contrails are the condensation of water vapor in jet engine exhaust, occurring at the lower temperatures which are found at high altitudes. Burning hydrocarbon fuels creates CO2 from the carbon in the fuel, and H20 from the hydrogen. In warm air, water vapor in jet exhaust dissipates before it cools from superheated (invisible) to saturated (visible). Contrails are condensation (con) trails.
Peter</HTML>
Re: Jet Vapor Trails
Posted by: David K Nergaard (IP Logged)
Date: April 30, 2003 10:40AM
<HTML>Contrails are the result of water vapor condensation, and are not limited to jets. Many WWII aircraft flew at altitudes where contrails were common. Whether they occur is a matter of relative humidity. If the humidity at the flying altitude is low, the water vapor in the exhaust can be absorbed by the air without condensing. If the air is super saturated, a single contrail can precipitate cloud forming over a large area.</HTML>
Re: Jet Vapor Trails
Posted by: Arnold Walker (IP Logged)
Date: May 01, 2003 10:46AM
<HTML>At 33,000 foot ,like commerical flights run.The temperature averages -60F.
So like David &Peter said we talking mighty dry air.
That is also the reason in addition to the pressure (boiling point of water) that if a person loses pressure. Your eyes themself dry out to the point of going blind within seconds(no tears no sight).....as if the breathing problems without a mask weren't enorgh.(Seven minutes to blackout.)In a pressure chamber,during training, it feels like your eyes are on fire and an elephant is sitting on your chest.About 80-90% of the water in the jet exhaust(or piston (P-51...warbird)engine exhaust with the 50psi supercharger pressure it took to fly at that height) drops out in those conditions.
Used to be an airman.</HTML>
So like David &Peter said we talking mighty dry air.
That is also the reason in addition to the pressure (boiling point of water) that if a person loses pressure. Your eyes themself dry out to the point of going blind within seconds(no tears no sight).....as if the breathing problems without a mask weren't enorgh.(Seven minutes to blackout.)In a pressure chamber,during training, it feels like your eyes are on fire and an elephant is sitting on your chest.About 80-90% of the water in the jet exhaust(or piston (P-51...warbird)engine exhaust with the 50psi supercharger pressure it took to fly at that height) drops out in those conditions.
Used to be an airman.</HTML>
Re: Jet Vapor Trails
Posted by: Brian Drake (IP Logged)
Date: May 07, 2003 07:53AM
<HTML>No, you're all wrong! You see, the government has put microchips in our bodies to control us, and the contrails from jets are actually chemical trails, as the planes spew out the chemicals the chips need to keep working, and they're doing this so we won't find out about the aliens they have kidnapped and have locked in Area 51! (I'm kidding, of course. The others have it right, it's just that I spent a number of years listening to late night radio and whenever the topic of contrails comes up, I just don't feel right unless some lunatic spouts a crazy theory about them.)</HTML>
Re: Jet Vapor Trails
Posted by: David K Nergaard (IP Logged)
Date: May 07, 2003 10:37AM
<HTML>You're right, talk radio is definately stratospheric! Down to earth, common sense hasn't been heard for years.</HTML>
Re: Jet Vapor Trails
Posted by: billy hanks (IP Logged)
Date: June 15, 2004 02:36PM
<HTML>why is it then some of the trails just stop and then begin again as fast as they stopped?</HTML>
Re: Jet Vapor Trails
Posted by: Steve Odrobina (IP Logged)
Date: December 15, 2005 10:08PM
<HTML>
The air coming out of the jet engine is extremely hot and highly compressed. As it exits the tail pipe it expands rapidly, and consequently, cools rapidly. Sometimes a jet flying at 35,000 ft or 40,000 ft leaves a condensation trial and sometimes it does not. The difference is the relative humidity of air the jet is flying in. At a low humidity the air can absorb the condensate, at a higher humidity it cannot.
In cold weather, when you exhale the moisture in the exhaled air condenses out and you see your breath. Your own con-trail.
former Naval Aviator</HTML>
The air coming out of the jet engine is extremely hot and highly compressed. As it exits the tail pipe it expands rapidly, and consequently, cools rapidly. Sometimes a jet flying at 35,000 ft or 40,000 ft leaves a condensation trial and sometimes it does not. The difference is the relative humidity of air the jet is flying in. At a low humidity the air can absorb the condensate, at a higher humidity it cannot.
In cold weather, when you exhale the moisture in the exhaled air condenses out and you see your breath. Your own con-trail.
former Naval Aviator</HTML>
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