isogonic line


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isogonic line

[′ī·sə¦gän·ik ‚līn]
(geophysics)
Any of the lines on a chart or map showing the same direction of the wind vector.
Any of the lines on a chart or map connecting points of equal magnetic variation.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

isogonal

isogonalclick for a larger image
A line drawn on a map or a chart joining points of equal variation (magnetic declination). On aeronautical charts, isogonic lines appear as irregular dashed lines (−3° E), and their values also are indicated alongside the lines. The annual change in their values is indicated at the bottom of the chart. Also called an isogonic line.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved