Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Curvature Of Earth  
User currently offlineKDTWFlyer From United States of America, joined Jun 2004, 828 posts, RR: 1
Posted (10 years 1 week 2 days ago) and read 12355 times:

At what altitude does the curvature of the earth become readily apparent? FL450 or higher than that? And I don't mean curvature as created by a wide angle lens.


NW B744 B742 B753 B752 A333 A332 A320 A319 DC10 DC9 ARJ CRJ S340
14 replies: All unread, jump to last
 
User currently offlineA/c train From United Kingdom, joined Jun 2001, 501 posts, RR: 4
Reply 1, posted (10 years 1 week 2 days ago) and read 12316 times:

Go and stand on satellite beach on the atlantic coast near cape canaveral and look out over the ocean, I would say around 6 ft ASL.

User currently offlineKDTWFlyer From United States of America, joined Jun 2004, 828 posts, RR: 1
Reply 2, posted (10 years 1 week 2 days ago) and read 12264 times:

Yes I know the curvature of the earth is visible when dealing with vast relatively planar surfaces such as the ocean's or very large lakes. I'm asking about at which altitude can one see an appreciably curving horizon and dark blue sky above? I've only been up in the range of FL390 and have not seen curvature but have seen slightly darker sky straight above indicated the increased altitude.


NW B744 B742 B753 B752 A333 A332 A320 A319 DC10 DC9 ARJ CRJ S340
User currently offlineUTA_flyinghigh From Tunisia, joined Oct 2001, 6495 posts, RR: 51
Reply 3, posted (10 years 1 week 1 day 23 hours ago) and read 12120 times:

You can also see it even when ground is not visible :

View Large View Medium
Click here for bigger photo!

Photo © William Ronciere


Taken @ FL390 onboard a 747-4B5  Big thumbs up.

UTA



Fly to live, live to fly - Air France/KLM Flying Blue Platinum, BMI Diamond Club Gold, Emirates Skywards
User currently offlineFLY 8 From Austria, joined Dec 2000, 329 posts, RR: 0
Reply 4, posted (10 years 1 week 1 day 21 hours ago) and read 12093 times:

a couple of years ago i was flying learjet 31a. cruising altitudes always between fl430 and fl490. max ceiling fl510. above fl 450 you clearly see a little curvature. but more impressive is the pretty dark sky right above you.


yes i can handle that alone. - - -famous last words
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 5, posted (10 years 1 week 1 day 17 hours ago) and read 12031 times:

This is a subject for some debate.

The true curvature of the earth would be the actual edge of the disk, a great circle of exactly the same diameter as the earth. What you can see from any airplane altitude is a horizon circling you at a few hundred miles away. A small circle.

From 35,000' the horizon is about 230 nautical miles away. So 230nm is the radius of a small circle of the earth's surface that you can see. To see the actual curvature, which is vastly greater than this circle you would have to be able to see the entire earth.

Actual earth-disk circumference is 21,600 nautical miles.
Earth's surface disk visible from FL350 is about 1446 nautical miles.

To claim you can see "the curvature of the earth" from low altitude, like a hundred thousand feet or so, is like putting your eye a couple of thousandths of an inch from a large beachball and believing that you can see its curvature. The math is about the same.

What looks curved is that the horizon is about 230nm away at your twelve o'clock but it is also 230 nm away at your eleven, and your one, and your ten, and your two, and your nine, and your three, and so on. If you can see all the way around (as in, from the basket of a balloon) the effect sort of goes away and you again get the sense that you are just hanging above a big (possibly curved) surface. The line of the horizon curves all the way around you, so hanging above a circle it will look curved.

Again, to see the true curvature, you'd have to be able to see the entire near side of the earth.





Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineTimz From United States of America, joined Sep 1999, 6771 posts, RR: 7
Reply 6, posted (10 years 1 week 8 hours ago) and read 11770 times:

"Again, to see the true curvature, you'd have to be able to see the entire near side of the earth."

Which you can only do from infinite distance, so...

How about this: how high must you be to make it obvious to the naked eye that the Earth isn't flat? If you were a quarter-radius above the surface, the horizon would be 37 degrees below a horizontal plane (i.e. a plane perpendicular to the vertical). An earth that only subtends 106.3 degrees at the viewer's eye is clearly unflat.

But what the original questioner was asking was: at what altitude does the horizon look curved. That's not so easy to answer.


User currently offlineDarkblue From United States of America, joined Sep 2003, 233 posts, RR: 10
Reply 7, posted (10 years 5 days 16 hours ago) and read 11568 times:

I'm not sure that you can see the curvature of the earth from any distance. Even if you were at some extreme distance in space, I don't believe you would have the depth perception to see that the edges are further away than the center. To the eye, the Earth would only appear as a flat disk. Take the moon for example, during a full moon your eyes cannot distinguish from a spherical object and a flat disk. The only thing that shows that it is a sphere is the shadow of the moon upon itself during other phases.

User currently offlineAmerican 767 From United States of America, joined May 1999, 3735 posts, RR: 12
Reply 8, posted (10 years 1 day 15 hours ago) and read 11344 times:
AIRLINERS.NET CREW
FORUM MODERATOR

The highest altitude I've ever been is 41000ft, at that point you still don't see the curvature of the earth but the sky above you starts getting dark. You would have to go above 50000ft to start seeing the curvature. These pictures, taken from Concorde, show:

taken in flight at 58000ft

View Large View Medium
Click here for bigger photo!

Photo © Sam Chui


taken in flight at 50000ft

View Large View Medium
Click here for bigger photo!

Photo © Bernard Charles



Now that Concorde is gone, you will never see this again. The highest altitude you will ever reach on any airliner is 43000ft.

Above 80000ft you are in space. Only astronauts and military pilots experience that.

Ben Soriano
Brussels Belgium




Ben Soriano
User currently offlineLapa_saab340 From Spain, joined Aug 2001, 390 posts, RR: 5
Reply 9, posted (10 years 1 day 13 hours ago) and read 11323 times:

You have to be careful when looking at pictures, using a wide angle lens will distort it an exaggerate the 'curvature', making it much more pronounced than your naked eye would see.

Also, 80,000ft is nowhere near space, the SR-71 Blackbird reportedly flew higher than this. Although there is no clearly defined boundary, 100,000m seems to be generally accepted as the edge of space (roughly 325,000ft or so). I think the X-15 still holds the altitude record for an airplane, 107,000m or so. Don't think SpaceShip One went that high.

Cheers


User currently offlineDarkblue From United States of America, joined Sep 2003, 233 posts, RR: 10
Reply 10, posted (10 years 1 day 13 hours ago) and read 11316 times:

You have to be careful when looking at pictures, using a wide angle lens will distort it an exaggerate the 'curvature', making it much more pronounced than your naked eye would see.

Yes, and the pictures shown in the earlier posts are a great examples of curvature due to lens distortion. The horizon appears to curve downward towards the edges of the picture. If you looking at the horizon with your naked eye, it would appear flat. If you really saw that downward curvature with your eye, then if you rotate around to look at the entire horizon, you would have a M.C. Escher type of optical paradox.

DB


User currently offlineBa97 From Canada, joined Apr 2004, 377 posts, RR: 0
Reply 11, posted (10 years 1 day 5 hours ago) and read 11265 times:

Looking out windows of planes, the only time I saw the horizon not "flat" but having a distinctive "curve" was on Concorde at 56,000ft. Optical illusion, too many fine drinks...I know it was not straight.

That said, it was way more impressive to see the deep deep blue to black sky and the clouds below passing like we were in a Dash 8 at 15,000ft.



there is economy class, business class, first class...then Concorde..pure class
User currently offlineArcano From Chile, joined Mar 2004, 2406 posts, RR: 24
Reply 12, posted (10 years 1 day 2 hours ago) and read 11252 times:

Excuse me, but when you stand in a beach and look to the horizon, don't you realize it's absolutely curve?

Altitude for that: 0

Is it only me????

BTW: If you are thinking maybe Columbus was wrong, you can also note the curve of the Earth during a moon eclipse: the shadow shape belongs to a sphere!



in order: 721,146,732,763,722,343,733,320,772,319,752,321,88,83,744,332,100,738, 333, 318, 77W, 78, 773 and 380
User currently offlineKDTWFlyer From United States of America, joined Jun 2004, 828 posts, RR: 1
Reply 13, posted (10 years 1 day ago) and read 11234 times:

Now this is high here ...

http://www.spaceadventures.com/media/photo/steps/mig-25/info/382

I would love to do alot of the things at this website

http://www.spaceadventures.com/ but it's all too damn expensive.



NW B744 B742 B753 B752 A333 A332 A320 A319 DC10 DC9 ARJ CRJ S340
User currently offlineGDB From United Kingdom, joined May 2001, 13165 posts, RR: 78
Reply 14, posted (10 years 7 hours ago) and read 11192 times:

On Concorde, you needed clear conditions, and really be above 55,000 feet.
So best seen on a BGI sector, usually clear when you reached top of descent at 60,000ft, as the longer BGI sectors usually reached this altitude, as opposed to 58,000ft maximum on a JFK sector.
Certainly, of my 7 flights, the best view was on mine and G-BOAE's final flight, last November to BGI.
To get the best discernible view you needed to look through 2 to 3 windows, positioning your head a few inches from the nearest window and looking through the immediate ones ahead of you as well.
Easier done on a nearly empty air test as I did on OAE last August, positioning yourself you are not in anyone's way or infringing on their personal space is do able if there are only about a dozen people in the whole cabin.
Even given the differing interpretations of what the curve of the Earth really is, if it can be seen on the ground or only in orbit or sub orbit, the sight from Concorde was sufficiently different compared to a normal view from an airliner, given good conditions you could make out a curving horizon in a way not possible from lower levels.
I saw it clearly on five flights, not as definable on one, difficult to make out on one.



Top Of Page
Forum Index

Reply To This Topic Curvature Of Earth
Username:
No username? Sign up now!
Password: 


Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)


Similar topics:More similar topics...
Curveture Of Earth @ 99,999 Feet? posted Thu Jul 20 2006 22:24:46 by Wardialer
Why Don't Anybody Build Airliners Out Of Steel? posted Sat Dec 9 2006 04:19:24 by 747400sp
Need Of Online SIDs/STAR Proceedures Please posted Thu Dec 7 2006 11:57:26 by Wardialer
Cost Of A 737-700 Type Rating posted Thu Dec 7 2006 01:27:30 by KingAirMan
Half Of NWA's Pilots Over 50? posted Wed Dec 6 2006 20:02:28 by Blackbird
Pitch Up (or Down) After Disegage Of Autopilot posted Wed Dec 6 2006 07:29:34 by SuseJ772
Cost Of A D-check? posted Fri Dec 1 2006 06:28:58 by Starstream707
Single Engine Airliners Of The Future? posted Wed Nov 29 2006 15:59:29 by DHHornet
777-300 Boxes On Top Of Fuselage posted Sun Nov 19 2006 17:10:06 by SABE
Other Uses Of Airplane Engines? posted Sat Nov 18 2006 10:01:00 by DIJKKIJK

Sponsor Message:
Printer friendly format