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 Isogonic Lines
 mawingho From Hong Kong, joined Jul 2012, 41 posts, RR: 0Posted Mon Aug 6 2012 09:33:52 UTC (3 years 9 months 4 weeks 8 hours ago) and read 5906 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?
 vikkyvik From United States of America, joined Jul 2003, 12146 posts, RR: 24 Reply 1, posted Mon Aug 6 2012 09:49:22 UTC (3 years 9 months 4 weeks 7 hours ago) and read 5890 times:

 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.

 I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
 bond007 From United States of America, joined Mar 2005, 5652 posts, RR: 8 Reply 2, posted Mon Aug 6 2012 09:52:41 UTC (3 years 9 months 4 weeks 7 hours ago) and read 5889 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!
 Mir From United States of America, joined Jan 2004, 22865 posts, RR: 53 Reply 3, posted Mon Aug 6 2012 15:50:17 UTC (3 years 9 months 4 weeks 1 hour ago) and read 5790 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
 bond007 From United States of America, joined Mar 2005, 5652 posts, RR: 8 Reply 4, posted Mon Aug 6 2012 16:46:44 UTC (3 years 9 months 4 weeks ago) and read 5774 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!
 SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 66 Reply 5, posted Mon Aug 6 2012 17:04:17 UTC (3 years 9 months 4 weeks ago) and read 5765 times:

 isotherms isotachs isopleths
 Happiness is not seeing another trite Ste. Maarten photo all week long.
 Starlionblue From Greenland, joined Feb 2004, 17665 posts, RR: 65 Reply 6, posted Mon Aug 6 2012 17:25:57 UTC (3 years 9 months 4 weeks ago) and read 5756 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."
 Rara From Germany, joined Jan 2007, 2512 posts, RR: 2 Reply 7, posted Wed Aug 8 2012 01:33:45 UTC (3 years 9 months 3 weeks 5 days 16 hours ago) and read 5534 times:

isobronts

 Samson was a biblical tough guy, but his dad Samsonite was even more of a hard case.
 SlamClick From United States of America, joined Nov 2003, 10062 posts, RR: 66 Reply 8, posted Wed Aug 8 2012 06:23:54 UTC (3 years 9 months 3 weeks 5 days 11 hours ago) and read 5491 times:

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

 Happiness is not seeing another trite Ste. Maarten photo all week long.
 KELPkid From United States of America, joined Nov 2005, 6833 posts, RR: 3 Reply 9, posted Wed Aug 8 2012 13:20:59 UTC (3 years 9 months 3 weeks 5 days 4 hours ago) and read 5431 times:

 Quoting SlamClick (Reply 8):Quoting Rara (Reply 7): isobronts isocubes: Line connecting points in a chilled beverage where freezing temperatures occur.

 Celebrating the birth of KELPkidJR on August 5, 2009 :-)
 vikkyvik From United States of America, joined Jul 2003, 12146 posts, RR: 24 Reply 10, posted Wed Aug 8 2012 13:53:44 UTC (3 years 9 months 3 weeks 5 days 3 hours ago) and read 5422 times:

 isohorny. i managed to make myself laugh and grimace at the same time with that one.
 I'm watching Jeopardy. The category is worst Madonna songs. "This one from 1987 is terrible".
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