1. What is Grid Convergence Angle?

The grid convergence angle (γ) is the angle between true north and grid north in a map projection. It accounts for the difference between meridians converging at the poles and the parallel grid lines of projected coordinate systems.

2. How Does the Calculator Work?

The calculator uses the grid convergence formula:

Where:

• \( \lambda \) — Longitude of the point (radians)
• \( \lambda_0 \) — Longitude of central meridian (radians)
• \( \phi \) — Latitude of the point (radians)
• \( \gamma \) — Grid convergence angle (radians)

Explanation: The formula calculates the angular difference between true north and grid north based on the point's position relative to the central meridian.

3. Importance of Grid Convergence

Details: Grid convergence is crucial for accurate surveying, navigation, and GIS applications where precise angle measurements between true and grid north are required.

4. Using the Calculator

Tips: Enter all angles in radians. For degree inputs, convert to radians first (radians = degrees × π/180). The central meridian is typically the center of your map projection zone.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between grid convergence and magnetic declination?
A: Grid convergence relates grid north to true north, while magnetic declination relates magnetic north to true north.

Q2: When is grid convergence zero?
A: Convergence is zero along the central meridian and at the equator.

Q3: How does convergence change with latitude?
A: Convergence increases with latitude, reaching maximum at the poles.

Q4: What's the practical significance of grid convergence?
A: It's essential for accurate coordinate transformations and aligning measurements between different reference systems.

Q5: Can I input degrees instead of radians?
A: The calculator requires radians, but you can convert degrees to radians by multiplying by π/180 (≈0.0174533).