# Vapor trails, military or commuter aircraft?

**URL:** <https://boards.straightdope.com/t/vapor-trails-military-or-commuter-aircraft/151055>\
**Category:** Factual Questions\
**Created:** [January 26, 2003, 4:52pm UTC](https://boards.straightdope.com/t/vapor-trails-military-or-commuter-aircraft/151055 "2003-01-26T16:52:49Z")\
**Posts on this page:** 5\
**Page:** 2

<div class="post-metadata">

**Author:** ![ralph124c](https://avatars.discourse-cdn.com/v4/letter/r/8797f3/32.png) [@ralph124c](https://boards.straightdope.com/u/ralph124c)\
**Post date:** [January 30, 2003, 6:35pm UTC](https://boards.straightdope.com/t/vapor-trails-military-or-commuter-aircraft/151055/21 "2003-01-30T18:35:58Z")

</div>

Many years ago, when the CONCORDE was getting ready for trials, several scientists raised an alarm about the possible effect of contrails. The arguement went that putting large quantities of water vapor into the upper atmosphere (I believe the CONCORDE cruises at \>65,000 feet) could result in changes to the earth’s climate. Specifically, the claim was made that the shading effect of the ice crystals would reduce the amount of sunlight hitting the earth, thus lowering the avaerage temperature.  
Is this theory still current?

---

<div class="post-metadata">

**Author:** ![InLikeFlynn](https://avatars.discourse-cdn.com/v4/letter/i/f19dbf/32.png) [@InLikeFlynn](https://boards.straightdope.com/u/InLikeFlynn)\
**Post date:** [February 1, 2003, 7:17am UTC](https://boards.straightdope.com/t/vapor-trails-military-or-commuter-aircraft/151055/22 "2003-02-01T07:17:26Z")

</div>

> [@](#):
>
> \*Originally posted by scr4 \*  
> \*\*Apparently not, because you and QED mentioned two different mechanisms. Are contrails made up of water contained in the jet exhaust, or was the water already in the atmosphere waiting for a nucleation site? \*\*

Who cares SCR4?  
That was not the purpose of the post!  
What are you just confrontational dork?  
If your not going to be helpful then mind your business!  
I have no time for anal-retentive types, life is short!

---

<div class="post-metadata">

**Author:** ![Zagadka](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zagadka/32/7272_2.png) [@Zagadka](https://boards.straightdope.com/u/Zagadka)\
**Post date:** [February 1, 2003, 7:22am UTC](https://boards.straightdope.com/t/vapor-trails-military-or-commuter-aircraft/151055/23 "2003-02-01T07:22:52Z")

</div>

> [@](#):
>
> \*Originally posted by InLikeFlynn \*  
> \*\*What are you just confrontational dork? \*\*

_lol_ :rolleyes:

Yep, this is what I come to SDMB for!

---

<div class="post-metadata">

**Author:** ![manhattan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/manhattan/32/7_2.png) [@manhattan](https://boards.straightdope.com/u/manhattan)\
**Post date:** [February 1, 2003, 2:49pm UTC](https://boards.straightdope.com/t/vapor-trails-military-or-commuter-aircraft/151055/24 "2003-02-01T14:49:09Z")

</div>

> [@](#):
>
> \*Originally posted by InLikeFlynn \*  
> \*\*Who cares SCR4?  
> That was not the purpose of the post!  
> What are you just confrontational dork?  
> If your not going to be helpful then mind your business!  
> I have no time for anal-retentive types, life is short! \*\*

I care. I care a lot. **scr4** asked a perfectly legitimate follow-up question.

More importantly, I care about you acting like a jerk in this forum. That is against our rules (check the rules you agreed to when you registered). You will stop. You will not repeat this behaviour.

---

<div class="post-metadata">

**Author:** ![paperbackwriter](https://avatars.discourse-cdn.com/v4/letter/p/53a042/32.png) [@paperbackwriter](https://boards.straightdope.com/u/paperbackwriter)\
**Post date:** [February 1, 2003, 10:44pm UTC](https://boards.straightdope.com/t/vapor-trails-military-or-commuter-aircraft/151055/25 "2003-02-01T22:44:39Z")

</div>

> [@](#):
>
> _originally posted by **ralph124c** _  
> Specifically, the claim was made that the shading effect of the ice crystals would reduce the amount of sunlight hitting the earth, thus lowering the avaerage temperature.  
> Is this theory still current?

Check the second link in my post above. There’s some evidence that in heavily-traveled areas it affects the average temperature.

[Previous page](https://boards.straightdope.com/t/vapor-trails-military-or-commuter-aircraft/151055.md?page=1)