|
|
Dirk Digler
Joined: 16 Mar 2001
Posts: 126
|
 Mon Mar 26, 2001 4:41 am
|
 |
|
3T3,
you just proved my point. you said "Second assumption--that the contrail has formed at 35,000 feet. "
we are trying to find the height of the contrail. the contrail is the unknown. your formulas are correct but you are not using them correctly.
use the same formulas and find THE HEIGHT OF THE CONTRAIL. dont assume anything about the contrail.
in mark sky's famous "hill and low chemtrail" photo he used the known constants (distance to hill and height of hill) to determine the height of the trail. i am asking you to do the same thing with my photo. i have given you the same knowns (distance to building, height of buliling) that mark sky has given you. so you should be able to determine the height of the trail. you shouldnt have to assume antyhing. mark sky didnt assume anything.
it is my contention that if the trail in mark sky's photo is at a low-level then the trail in my photo can be at a low-level. why do you assume my trail is at 35,000 ft? you didnt make the same assumption about his.
[Edited 2 times, lastly by Dirk Digler on 03-25-2001] |
| |
|
|
cydoniaquest
Joined: 12 Aug 2000
Posts: 797
Location: nowhere |
|
Mon Mar 26, 2001 4:45 am
|
|
|
AAAAH HA !! 
I think I see what you're saying 3T3, (drew it out on paper to get the visual). But the problem with this equation is that you are still assuming facts not in evidence.
For example, you assume the height of the contrail...but this is the very thing that the equation attempts to find out!.
Now, we can divide 30 by 50 and take the inverse tangent to get the angle, but we still don't know the distance of the adjacent side of the larger right triangle to a point directly beneath the trail....and we still don't know the height of the contrail from a point directly underneath it.
In other words, you have a common angle, but you still need at least one other side of the triangle to solve the problem. Again, you can't just assume the height of the contrail....this defeats the purpose of the whole thing!
|
| |
|
|
3T3L1
Joined: 08 Mar 2001
Posts: 1344
Location: Lubbock, Texas |
|
Mon Mar 26, 2001 6:38 am
|
|
|
Technically, you're right, but the whole discussion started with Mark Sky's statement:
"For these trails to be at 35000 feet elevation, they would have to be 50 to 60 miles in the distance."
What he's saying is that there is a restricted range of altitudes at which true contrails can form. He has taken 35,000 feet as a reasonable average. If you take the values at either end of the permitted range, you come up with a range of distances at which true contrails would be located. He's saying that, if these are true contrails, they must be about 50 miles away from his camera. He doubts that he would have seen that much clarity and definition in the trails if they really had been that far away.
Top Gun says that it's possible to see objects 150 miles away. I'm not a pilot, but from the fifth floor of our Medical School, it's easy to see 50 miles on most days. However, looking through that amount of atmosphere, I would be surprised to see true contrails that looked as clear and white as Mark's did. |
| |
|
|
Dirk Digler
Joined: 16 Mar 2001
Posts: 126
|
|
Mon Mar 26, 2001 8:03 am
|
|
|
i do not think that mark sky's statement of it has to be 60 miles away is correct, however, even if it is, it is still reasonable. you would be surprised, sometimes something will look 10 or 20 miles away. but you look down at the DME and it says 40.
remember also, that the part of the trail that "has to be 60 miles away" is almost to the horizon (the part that touches the hill).
very possible.
"they must be about 50 miles away from his camera. He doubts that he would have seen that much clarity and definition in the trails"
to give you an example. i do a lot of GA flying on the east coast of florida. on a good day you can see all the way to the other side of FLA. and this is at a relatively low altitude. this distance is roughly 110 nautical miles.
[Edited 1 times, lastly by Dirk Digler on 03-26-2001] |
| |
|
|
3T3L1
Joined: 08 Mar 2001
Posts: 1344
Location: Lubbock, Texas |
|
Mon Mar 26, 2001 8:21 am
|
|
|
I think Mark Sky used graph paper to estimate the distance. My trusty calculator gives a value closer to 38 miles.
We'll just have to disagree on the effect of the atmosphere on the quality of "seeing." I would expect definition to degrade and the color to shift more and more toward blue when looking through that much air. |
| |
|
|
Dirk Digler
Joined: 16 Mar 2001
Posts: 126
|
|
Mon Mar 26, 2001 8:51 am
|
|
|
thanks for the post 3T3.
it seems as though we are slowly moving towards a good working environment. i hope this is the case as i do enjoy discussing these issues with you folks. well, most of you!
anyway, 38 miles is even more reasonable and would not be unusual.
"We'll just have to disagree on the effect of the atmosphere on the quality of "seeing." I would expect definition to degrade and the color to shift more and more toward blue when looking through that much air."
well we will have to disagree on this point. you can either take my word for it or not (but if you think that i am lying then you have to think that all pilots are lying because they will all tell you the same thing). it is very possible to see objects, including contrails, at very large distances. i witness this almost every day. we have something called TCAS which shows us the position of other aircraft. we can sometimes see aircraft 40 miles away on the screen and their contrails are easily seen.
[Edited 2 times, lastly by Dirk Digler on 03-26-2001] |
| |
|
|
3T3L1
Joined: 08 Mar 2001
Posts: 1344
Location: Lubbock, Texas |
|
Mon Mar 26, 2001 3:27 pm
|
|
|
Sadly, we're having problems with terminology again, Mr. Digler. I'm not disputing that you (and Top Gun) can see things at 40, 110 or even 150 miles. It's the QUALITY of the seeing which I'm talking about. Movement of minicells of air will blur the detail, just as they cause stars to twinkle. Diffraction (refraction? I forget the correct term...)will cause the apparent color to move toward blue. |
| |
|
|
 
|
|
 Goto page Previous
1, 2, 3, 4
All times are GMT. The time now is Sat May 26, 2012 2:17 am
|
|
|
|
|
Login
