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Isogonic Lines  
User currently offlinemawingho From Hong Kong, joined exactly 2 years ago today! , 41 posts, RR: 0
Posted (1 year 11 months 2 weeks 5 days 22 hours ago) and read 3274 times:

From Wikipedia http://en.wikipedia.org/wiki/Magnetic_variation

"Magnetic declination is the angle between magnetic north (the direction the north end of a compass needle points) and true north. The declination is positive when the magnetic north is east of true north. The term magnetic variation is a synonym, and is more often used in navigation. Isogonic lines are where the declination has the same value, and the lines where the declination is zero are called agonic lines."

I still do not quite understand the last sentence about Isogonic Lines, anyone knows?

10 replies: All unread, jump to last
 
User currently offlinevikkyvik From United States of America, joined Jul 2003, 9763 posts, RR: 27
Reply 1, posted (1 year 11 months 2 weeks 5 days 21 hours ago) and read 3258 times:
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Quoting mawingho (Thread starter):
Isogonic lines are where the declination has the same value, and the lines where the declination is zero are called agonic lines."

Sounds like isogonic lines are the set of continuous points where the magnetic variation stays constant.

So if you start somewhere with a magnetic variation of, say, +5 degrees, then the line you follow to maintain a magnetic variation of +5 degrees is an isogonic line.



"Two and a Half Men" was filmed in front of a live ostrich.
User currently offlinebond007 From United States of America, joined Mar 2005, 5395 posts, RR: 8
Reply 2, posted (1 year 11 months 2 weeks 5 days 21 hours ago) and read 3257 times:

Agonic lines are simply joining points where the declination is zero ... i.e. no difference between true and magnetic.

A compass will point to true North on this line.

Jimbo

[Edited 2012-08-06 09:54:07]


I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
User currently offlineMir From United States of America, joined Jan 2004, 21490 posts, RR: 56
Reply 3, posted (1 year 11 months 2 weeks 5 days 15 hours ago) and read 3158 times:

If you're familiar with contour lines on a map, isogonic lines use the same principle. Just like every point on a contour line has the same altitude, every point on an isogonic line has the same magnetic variation.

-Mir



7 billion, one nation, imagination...it's a beautiful day
User currently offlinebond007 From United States of America, joined Mar 2005, 5395 posts, RR: 8
Reply 4, posted (1 year 11 months 2 weeks 5 days 14 hours ago) and read 3142 times:

Quoting Mir (Reply 3):
If you're familiar with contour lines on a map

... or weather of course, showing the pressure with isobars ... iso meaning 'equal'


Jimbo



I'd rather be on the ground wishing I was in the air, than in the air wishing I was on the ground!
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 5, posted (1 year 11 months 2 weeks 5 days 14 hours ago) and read 3133 times:

isotherms
isotachs
isopleths



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineStarlionblue From Greenland, joined Feb 2004, 16991 posts, RR: 67
Reply 6, posted (1 year 11 months 2 weeks 5 days 14 hours ago) and read 3124 times:

Here's an example of isogonic lines in the United States. As mentioned magnetic variation is the same along the lines.

Quoting SlamClick (Reply 5):

isotherms
isotachs
isopleths

isohyets.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineRara From Germany, joined Jan 2007, 2054 posts, RR: 2
Reply 7, posted (1 year 11 months 2 weeks 4 days 6 hours ago) and read 2902 times:

Quoting Starlionblue (Reply 6):
isohyets

isobronts  



Samson was a biblical tough guy, but his dad Samsonite was even more of a hard case.
User currently offlineSlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 68
Reply 8, posted (1 year 11 months 2 weeks 4 days 1 hour ago) and read 2859 times:

Quoting Rara (Reply 7):
isobronts

isocubes: Line connecting points in a chilled beverage where freezing temperatures occur.



Happiness is not seeing another trite Ste. Maarten photo all week long.
User currently offlineKELPkid From United States of America, joined Nov 2005, 6343 posts, RR: 3
Reply 9, posted (1 year 11 months 2 weeks 3 days 18 hours ago) and read 2799 times:

Quoting SlamClick (Reply 8):
Quoting Rara (Reply 7):
isobronts

isocubes: Line connecting points in a chilled beverage where freezing temperatures occur.

isolate    (myself from this thread!)



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlinevikkyvik From United States of America, joined Jul 2003, 9763 posts, RR: 27
Reply 10, posted (1 year 11 months 2 weeks 3 days 17 hours ago) and read 2790 times:
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isohorny.

i managed to make myself laugh and grimace at the same time with that one.



"Two and a Half Men" was filmed in front of a live ostrich.
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