reply to post by Stewie
Let 'em chew on this one.
Let’s all take a moment to take a look at what I’m trying to describe. I’ll try to think like the pilot guys want me to think for a second
here…I’ll delve into a little minutiae, but not too much. This image was taken on the afternoon of June 24, 2010. This is a “low spray” day,
most days would be worse than this. I may not be able to tell what the altitude is of these contrails, but I can certainly tell what the weather
conditions were on that day.
[atsimg]http://files.abovetopsecret.com/images/member/2e5a54f86331.jpg[/atsimg]
To all the laypeople out there, “sounding” data refers to the information gathered by weather balloons all over the world. You can check your own
data from your area for any given day at the below link:
weather.uwyo.edu...
The timestamps of the snapshots of the atmospheric data are given in “Z” time…that’s just referring to Greenwich Mean Time…0Z indicates zero
hour at Greenwich (on the next day, because they’re ahead of us), or late afternoon out here in the Pacific Northwest (the day before 0Z time). 12Z
indicates early morning my time of the same day.
Regarding contrail formation, we’re interested in temperature, relative humidity (RH), dew point and altitude. For contrails to form, they need to
have the right temp, but there also needs to be the right RH. For perspective, a dry relative humidity is considered to be areas like parts of
Arizona with a RH of 50, Antarctica has the lowest in the 20s.
Dew point indicates the temperature needed to be reached for the amount of humidity in the air, relative to the air temperature, to reach the
saturation point…aka the temp needed to be reached for condensation to form.
So, armed with my photo from June 24 2010, I pulled up the below data from the above site. Note the temperatures, especially note the RH at
altitude…and finally, note the Dew Point. With a relative humidity in the low 20s and a Dew Point never being reached, can any of those pilots tell
me when June 24 could support the conditions required to make so many contrails at ANY altitude?
We had low humidity and the dew point was never reached, so contrails should not have formed at all.
Please Clarify...this is directed at the Flying Circus.
72694 SLE Salem Observations at 00Z 25 Jun 2010
-----------------------------------------------------------------------------
PRES HGHT TEMP DWPT RELH MIXR DRCT SKNT THTA THTE THTV
hPa m C C % g/kg deg knot K K K
-----------------------------------------------------------------------------
387.0 7690 -25.9 -30.9 63 0.76 271 23 324.3 327.1 324.4
353.0 8348 -31.3 -38.3 50 0.40 276 23 325.6 327.2 325.7
338.0 8654 -33.7 -41.7 44 0.29 278 24 326.4 327.6 326.5
315.0 9144 -36.5 -50.5 22 0.12 282 24 329.2 329.7 329.2
300.0 9480 -39.5 -55.5 17 0.07 285 24 329.6 329.9 329.6
290.0 9711 -41.7 -59.7 12 0.04 289 24 329.6 329.8 329.7
275.3 10058 -44.5 -61.0 14 0.04 295 24 330.5 330.7 330.5
254.0 10596 -48.9 -62.9 18 0.03 264 27 331.7 331.9 331.7
251.2 10668 -49.3 -62.6 20 0.03 260 27 332.1 332.3 332.2
250.0 10700 -49.5 -62.5 20 0.03 265 28 332.3 332.5 332.4
217.9 11582 -55.4 -67.8 20 0.02 270 23 336.5 336.6 336.5
200.0 12130 -59.1 -71.1 20 0.01 295 26 339.0 339.1 339.0
198.0 12192 -59.5 -71.2 21 0.01 295 26 339.4 339.4 339.4
194.0 12320 -60.3 -71.3 22 0.01 295 27 340.1 340.1 340.1
188.6 12497 -60.0 -71.5 21 0.01 295 24 343.3 343.4 343.4
184.0 12650 -59.7 -71.7 19 0.01 285 21 346.2 346.3 346.2
181.0 12753 -58.7 -70.7 20 0.02 278 19 349.5 349.6 349.5
179.6 12802 -59.0 -71.0 20 0.01 275 18 349.8 349.9 349.8
175.0 12964 -59.9 -71.9 19 0.01 264 21 350.9 350.9 350.9
171.1 13106 -58.5 -70.5 20 0.02 255 23 355.4 355.5 355.4
weather.uwyo.edu...
edit on 25-2-2011 by Yankee451 because: added: "...this is directed at the Flying Circus."