Lambert Conformal Conic Projection

The Lambert Conformal Conic projection is designed for use in middle latitudes. Its key features and characteristics are as follows:

Characteristics

• Standard Parallels: Two standard parallels are chosen, located 1/6 from the top and bottom of the projected area.
• Parallels: Represented as concentric arcs with an apex at the center. These arcs are not equidistant from each other.
• Meridians: Straight lines that converge toward the poles and are correctly spaced.

Scale:

• Correct at Standard Parallels: The scale is accurate at the selected two standard parallels.
• Between the Standard Parallels: Scale contracts (RF increases).
• Outside the Standard Parallels: Scale expands (RF decreases).
• At Poles: Scale is minimal.
  For practical purposes, the scale is considered constant.

Convergency:

• Correct at Parallel of Origin.
• Towards the Pole: Convergency reduces.
• Towards the Equator: Convergency increases.

Rhumb Line (RL):

• RLs are straight lines along parallels and meridians.
• Elsewhere, RLs curve concave to the pole.

Great Circle (GC):

• Near the parallel of origin, GCs are straight lines.
• Away from it, GCs form gentle curves concave to the parallel of origin.
• For practical purposes, GCs are considered straight lines.

Limitations:

• Chart size is designed to ensure scale error remains less than 1%.
• An artificial grid is required for plotting purposes.

Uses:

• Air Routes: Widely used for air route planning. Jeppesen charts are based on this projection.
• Great Circle Segments: Air route segments are GC segments, with tracks and bearings measured at the segment’s mid-longitude.
• Ease of Plotting: No convergency or conversion angle is needed to plot VOR radio bearings.
• State Grid Systems: In the U.S., the National Geodetic Survey uses this projection for defining grid-coordinate systems in states elongated west to east.

Advantages Over Mercator Projection:

1. Ease of Plotting Radio Bearings: Radio bearings can be plotted directly.
2. Constant Scale: Distance measurement is more straightforward.
3. GC Tracks: Great Circle tracks can be flown.
4. High Latitudes: Suitable for use in higher latitudes, where Mercator charts distort significantly.

Comparison with Mercator Projection:

• Mercator Projection: Commonly used for maritime navigation because Rhumb Lines plot as straight lines.
• Lambert Projection: Preferred for aviation due to its ability to represent GC tracks as nearly straight and more accurate distance scaling in middle and higher latitudes.