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they all lack one vital bit of information about the length of time a contrail will last for.
Originally posted by Chadwickus
reply to post by backinblack
Like how long is a piece of string or how big is a cloud.
You know it can't be answered, so stop being a smart arse.
Originally posted by pianopraze
reply to post by Chadwickus
Ok, re-watched video and read your links; thank you for the info.
He is saying that on many days he observed contrails, the humidity was "well below 60 percent" That graph is basically an explanation of what he asserted not the observations themselves (the graph is reprinted here in black and white). All the papers I could find agree with the assertions of the maker of the video.
So with all that information, you have still not shown how contrails could form when the conditions do not exist. You have only made me understand the video, much better.
Totally off topic... I love the NASA educational papers for school children I found researching this post which only reference other propaganda papers
ETA. I'm going to be busy this weekend volunteering so I'll check back in Sunday. It's 4:35 am so I'm going to bed nowedit on 25-3-2011 by pianopraze because: (no reason given)
Rosalind Peterson of California Skywatch was a certified U.S.D.A. Farm Service Agency Crop Loss Adjustor working in more than ten counties throughout California. She now spearheads a watchdog group that monitors uncontrolled experimental weather modification programs, atmospheric heating and testing programs, and ocean and atmospheric experimental geoengineering programs Peterson is at the forefront of the chemtrail research field and how the unexplained patterns that scar our skies are "causing detrimental human health effects and environmental degradation."
Originally posted by djcarlosa
reply to post by backinblack
That's OK I do have a source that say's exactly how long a normal contrail will last for and the main factors which also puts to rest how you can extend the length a contrail can last for and believe me it can't be debunked and that's why I'm being ignored.
Originally posted by Essan
reply to post by djcarlosa
Contrail persistence varies just as cloud persistence varies. There may be a computer algorithm that can determine how long a contrail should last under given conditions, but I'm not sure what the point would be since atmospheric conditions do not remain static...
Relative humidity measurements in the upper troposphere are particularly challenging due to low temperatures and low water vapour concentrations. Different types of sondes are subject to different error sources, such as time lag, chemical contamination, sensor ageing, etc., resulting in the need for different bias correction methods. For instance, while the more widely-used Vaisala RS80-A sondes show a large temperature-dependent error, this problem is much smaller for the RS80-H sondes used in the UK (Miloshevich et al., 2001, Wang et al., 2002). The main error source for these sondes is the chemical contamination originating from non-water molecules emitted from the packaging material that occupy binding sites in the sensor polymer, leading to a dry bias in the RH measurement.
300.0 9450 -41.1 -56.1 18 0.06 250 78 327.3 327.6 327.3
289.0 9704 -42.7 -58.7 16 0.05 249 85 328.6 328.8 328.6
267.0 10235 -47.1 -62.1 16 0.03 247 98 329.6 329.8 329.7
251.0 10644 -49.1 -63.1 18 0.03 245 109 332.6 332.7 332.6
250.1 10668 -49.3 -63.3 18 0.03 245 110 332.6 332.8 332.6
250.0 10670 -49.3 -63.3 18 0.03 245 108 332.6 332.8 332.6
216.0 11608 -57.1 -68.1 24 0.02 241 110 334.7 334.8 334.8
206.6 11887 -58.7 -69.7 23 0.02 240 110 336.5 336.6 336.5
200.0 12090 -59.9 -70.9 22 0.01 240 117 337.8 337.8 337.8
The distribution of layer-widths has a strong peak at about 50 m and an underlying broader distribution with values up to several kilometres.
Originally posted by Phage
As far as the persistent claim (pun intended) that 60% humidity is required for contrail persistence, it just is not true. I think it comes from misreading the Appleman chart. The relative humidity values provided by radiosondes are RHW (relative humidity over water). Persistence is determined by a different value, RHI (relative humidity over ice). So again, as with attempting to use dew point from the skew-T charts (or radiosonde data), no direct comparison can be made. In fact, ice saturation can occur with RHW values of less than 60%
With the inaccuracies inherent in the instrumentation, the limited area of the sampling, the low resolution of the sample, and the fact that weather conditions can and do change in a matter of hours it is apparent that there are limitations of the ability to forecast contrail formation (and persistence) based on standard upper air soundings. It is apparent that using upper data in an attempt to disprove persistent contrails can be no more effective.