Originally posted by Phage
reply to post by BoboIsBlue
You may be confused about how to read the chart. The vertical axis is altitude (expressed as atmospheric pressure) and the horizontal axis is
temperature. Data points which occur to the right of the 100% humidity line will not produce contrails. Data points to the left of the 0% line will
always produce contrails. Those in between might produce contrails.
The sample actually shows that there may be contrails formed above 260hPa which corresponds to an altitude of about 32,000 feet. It also shows that
there will always be contrails at altitudes of 38,000 feet and higher and that persistent contrails can form at altitudes of 37,500 feet (or higher).
Transcontinental flights are often made at 32,000 feet and higher, 39,000 feet is not at all unusual. These flights often fly over the Chicago
area.
It would be helpful if you could provide the dates and times (and the station) for the soundings that showed no possibility for contrail formation
last summer.
I am not confused.
Before I comment, I just want to be sure I have you straight...
1) Ok, I admit temperature usually decreases with altitude (increases likelihood of contrails).. but only up about to 17,000 feet at which point
temperature usually increases slightly through the maximum FAA rated altitudes (say 45k feet if you include using oxygen masks).
2) but
pressure DECREASES with altitude (decreases likelihood of contrails)... If you want to boast these lofty altitudes above 35k feet,
pressure is VERY low. In fact, usually in the single digits hPa (points at which the Appleman charts indicate NO CONTRAILS) right?
3) I quote you, "there will always be contrails at altitudes of 38,000 feet and higher".. you are saying that the Appleman Chart supports this? Do
you at least want to limit that claim to the Winter months or areas of high pollution? I mean REALLY? Are there not a huge number of instances across
the country of temperatures hotter than -40 degrees and pressures of less than 250hPa in the typical and even the higher range of cruising altitudes?
Really????
I think three is enough to expect you to keep track of. Confirm ALL three for the record please, then I will respond accordingly. Take your time.
Get some help from the others first. Don't misstep here. Don't change course.
I really don't see how the anti-debunkers did not serve you your shorts years ago.
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Note: Oh, and I love your signature Phage! "Get your facts first, then you can distort them as you please."
It's apropos! (look that up)
Must you be so blatant?
[edit on 18-1-2009 by BoboIsBlue]
There's a lot more than just temp and RH involved - as we've found from decades of research. 
