Chapter 11 : Convergency and Conversion Angle Flashcards
QB: What is Convergency?
Angle of inclination measured between 2 meridians at a give latitude.
Difference between G.C. direction of G.C., measured at each meridian.
QB: Convergency =
Points on same latitude = d.long X sin. lat.
Points on diff. latitude = d.long X sin. (mean lat.)
QB: Convergency varies as the -
Sine of Latitude
Convergency at Equator -
0
Convergency will increase with -
Increase in -
- Latitude
- d. long.
What is the main effect of Convergency?
Since meridians define direction with reference to True North - And since Meridians converge - The direction of a Great Circle constantly changes.
Thumb rule for Great Circle direction -
G.C. is -
Concave to equator
Convex to poles
Change in direction of Great Circle in the N.H. -
In the N. H. - [Concave to Equator]
Direction of Easterly G.C. - Increases
Direction of Westerly G.C - Decreases
Change in direction of Great Circle in the S.H. -
In the S. H. - [Concave to Equator]
Direction of Easterly G.C. - Decreases
Direction of Westerly G.C - Increases
Thumb rule for Rhumb line direction -
R.L. is -
Convex to equator
Concave to poles
Comparision bet. G.C. and R.L. bet. two points 1 -
Which is closer and farther from equator -
R.L. nearer to equator
G.C. farther from equator
If direction is measured of great circle at 2 selected meridians, will there be difference between 2 directions?
Yes.
Difference in direction at 2 points will be the -
Convergency between the 2 meridians.
QB: What is Conversion Angle?
Difference between -
GC. direction and Rhumb line direction joining 2 points.
QB: Conversion Angle =
1/2 Convergency
QB: Conversion Angle increases with -
- Increase in Latitude
- Increase in d. long
