Which of the diagrams most accurately represents the great circle route from A to B on a Lambert conformal conic chart?
PROPERTIES OF A LAMBERT CHART | |
Scale | Correct on the standard parallels. Contracted within the standard parallels. (least then 1% at parallel of origin). |
Orthomorphic | Yes. All charts used for navigation must be. |
Graticule | Meridians are straight lines, originating from the pole. Parallels are arcs of circles, centred at the pole. |
Parallel of Origin | Mathematical basis of projection. Assumed to be halfway between the 2 standard parallels. |
Chart Convergence | Constant across the chart = Earth Convergence. |
Rhumb Lines | Meridians are straight lines. All other Rhumb Lines are concave to the pole (i.e. parallels of latitude). |
Great Circles | Meridians are straight lines. |
Therefore we are looking for a curve concave to the parallel of origin. This means that for latitudes greater than the parallel of origin curve should bulge towards pole. Diagram 2 has convex curve to the parallel of origin, Diagram 3 has partly convex curve to the parallel of origin and Diagram 4 has a straight line. Diagram 1 is the one we are looking for.
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