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3T3L1
Joined: 08 Mar 2001
Posts: 1344
Location: Lubbock, Texas |
 Wed Oct 03, 2001 4:20 pm
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In case you can't drive along the same bearing you used to sight the elevation of the c-trail:
Use your clinometer as a protractor. Holding the clinometer in a plane parallel to the plane of the ground, point the 0° mark along the bearing on which you will be driving. Sight along the protractor to determine the relative position of the c-trail to the bearing on which you will be driving. Call that angle the "variance". Call the variance at the site farther from the c-trail f, and the variance at the site nearer to the c-trail n.
Call the distance you will be driving d'. When it comes time to figure the altitude of the c-trail, you can use this formula to convert d' to d: d=(d')(cos[f]) Please note, this formula just gives a ballpark estimate of what d should be.
If you want to be precise, d equals:
d'/(cosf-cosn)
[sinf/(sinn+sinf)]+[cosf/(cosf-cosn)]
I have formulated a Microsoft Excel spreadsheet for calculating altitude. All you have to do is plug in the numbers for the far angle of elevation, the near angle of elevation, the far angle of variance, the near angle of variance, the distance driven, and the altitude/elevation at your location. If you have Microsoft Excel and would like the spreadsheet, e-mail me and I'll send it to you.
[Edited 10 times, lastly by 3T3L1 on 10-11-2001] |
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3T3L1
Joined: 08 Mar 2001
Posts: 1344
Location: Lubbock, Texas |
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Thu Oct 11, 2001 2:56 pm
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Oops! I forgot two important considerations in my calculation of altitude:
1. Because each arm of the X was probably at a different altitude, siting on the place where the X crossed was a not a good idea in this instance. As I drove toward the X, the place where the trails appeared to cross would have been different at the place I took the far angle of elevation and the place I took the near angle of elevation.
2. The altitude/elevation of Lubbock itself is not a trivial part of the calculation. So, in the future, I will be adding 3,282 feet above sea level to my calculated altitude. (That's the altitude/elevation at the airport. If you've ever been to Lubbock, you know it doesn't vary much from that value across the entire county.)
[Edited 1 times, lastly by 3T3L1 on 10-11-2001] |
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Stuart-Allsop
Joined: 17 Oct 2001
Posts: 12
Location: Santiago, Chile |
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Thu Oct 18, 2001 6:45 pm
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Hi everyone. I'm a newcomer here, so please take it easy on me if I cover ground already covered elsewhere.
I noticed that somone suggested using the ADDS service to determine temperature and humidity at certain places and altitudes. I wanted to point out that this is not necessarily going to give you an accurate reading!
ADDS is a service offered by the FAA for pilots to use in flight planning, and only gives very general, aproximate conditions over very wide areas. It is an experimental system, based on a mixture of computer predictions and computer interpolations of real data. The disclaimers on the web site include statements such as: "The Federal Aviation Administration funds and directs the Aviation Digital Data Service and the experimental products that it displays." And "These products have not been develope by and are not endorsed by the National Weather Service". And also: "Caution: This site contains experimental products and services."
At best, ADDS will give you a rough aproximation of the average conditions at a certain place, but they will not necessarily be accurate, and certainly not for a very small volume of sky. Also, given that atmospheric conditions are highly variable, and can vary dramaticaly even over very short distances, it is quite possible that the readings might be valid for one point in the atmosphere, but entirely different for a point just a few feet away. |
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3T3L1
Joined: 08 Mar 2001
Posts: 1344
Location: Lubbock, Texas |
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Sun Nov 18, 2001 11:19 pm
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Here's another example of a chemtrail at low humidity. This one was observed at 15:25 CST on 11/18/01 east of Lubbock. I sighted on the top of the segment in the center of the picture. Near elevation was 24.8° and near variance from due east was 6°. I drove 2.78 miles due east. At that point, far elevation was 37° and far variance from due east was 10°.
Using my Excel formulas, the calculated height of the trail above sea level was 20,628 feet. ADDS said that the relative humidity at this altitude and at this time was between 0.2 and 0.3. The temperature at that altitude was between -15 and -25 degrees centigrade.
The trail lasted for about an hour.
[Edited 4 times, lastly by 3T3L1 on 11-19-2001] |
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3T3L1
Joined: 08 Mar 2001
Posts: 1344
Location: Lubbock, Texas |
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Thu Jan 17, 2002 5:44 am
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Thanks to Hoople on another thread, I have realized that I neglected to give instructions for using the clinometer method to determine trail altitude. Here goes. 
To make an inexpensive clinometer, take two clear plastic protractors and align them back-to-back. Attach them at both ends of the straightedge using doublesided sticky tape. Attach a weight to the hole in the center of the straightedge using thread or fishing line. Be sure the weight will swing freely when you insert a fingernail between the protractors. Re-number the protractor such that 90° is now 0°, 80° is now 10°, etc. You want the horizon to read as 0° and straight overhead to read as 90°.
To use the clinometer, insert your fingernail between the protractors, so that the weight swings freely. Sight along the straightedge, so that it points directly from your eye to a distinctive portion of the c-trail in question. Without changing the alignment, slide your fingernail out from between the protractors, and pinch them together on the fishing line. You can now read the elevation of that portion of the c-trail by looking at the position of the line on the degree scale of the protractors.
To measure the altitude of a trail, you will need the clinometer and a motor vehicle.
1. Pick out a distinctive feature of the trail and site in on it with the clinometer. Call this angle #1.
2. Record the exact mileage on your vehicle's odometer. Drive about 2-5 miles (in a straight line--no curves or turns) in the direction of the distinctive feature. When you reach a place where it's safe to take the second clinometer reading, record the exact mileage on your vehicle's odometer.
3. Measure the elevation of the distinctive feature at the second location and call it angle #2.
4. Put in a call to me and I will calculate the elevation of the trail for you. (Lots of math involved, but I have an Excel program, so I can just plug in the numbers.)
Further instructions: I am assuming you are driving directly toward the trail. If the distinctive feature of the trail is off at a slight angle from your direction of travel, use the clinometer as a protractor to measure that angle (call it angle #3) at your first location and measure it again (call it angle #4) at your second location. My Excel program can handle it.
I'm serious about having you call me. If you plan to do this, use the Message feature of this board and ask me for my phone number. If you'd rather have me send you a copy of the Excel calculation matrix, I can send it to you on a floppy.
[Edited 2 times, lastly by 3T3L1 on 01-17-2002] |
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canex
Joined: 26 Oct 2000
Posts: 164
Location: USA |
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Sat Jan 19, 2002 4:31 am
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I found a new contrail forecast site at http://www-pm.larc.nasa.gov/
They plot areas of persistent contrails every hour. |
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3T3L1
Joined: 08 Mar 2001
Posts: 1344
Location: Lubbock, Texas |
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Wed Jan 23, 2002 9:52 pm
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Here is something which clears up a big mystery. As noted above, the relative humidity at 20,000 feet in the broken trail picture above was between 0.2 and 0.3 according to the ADDS map at the time. That is way too low for persistent contrail formation. It turns out that the ADDS humidity measurements may not be so accurate after all. The quote is from Chickiedeb at http://cdebsjournal.topcities.com/RHaltitude.htm
quote:
...I have engaged in e-mail exchanges with Dr. Patrick Minnis of NASA/ASD. Dr. Minnis is involved in the study of remote sensing of the atmosphere and the Earth's surface. His research focuses on the characterization and measurement of clouds, aerosols, and radiation for the study of climate.
I asked him WHY the ADDS pages will show relative humidity at values of 50%+ that correlate with reports of "chemtrails,"...[comment here was deleted by 3T3L1]... Not being scientifically or meteorologically inclined, I assumed that the information from the ADDS pages was close to exact. It turns out I was wrong and technology hasn't advanced yet to the point I assumed it had. This is what Dr. Minnis clarified:
"Your notice about the 50% RH is typical. If you read the discussion on the web site, it talks about the humidity problems. There is a well-known bias in the relative humidities measured at high altitudes. The measurements are generally drier than the true value (based on research quality instruments vs operational ones). High altitude humidity was never a big factor in weather forecasts until recently. SO, people are trying come up with better operational measurement systems. When those measurements are put into a computer model to give values all over the country , it tends to reinforce the dry bias. That is why you get RH = 50% and contrails. The true value has to be greater than 100% for the contrails to persist for very long (more than a few minutes). At those cold temperatures, a small error in moisture measurement leads to a large error in RH.
[Edited 1 times, lastly by 3T3L1 on 01-23-2002] |
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