What is meant by Grid Magnetic Angle?

Grid Magnetic Angle refers to the angular difference in direction between grid north, which is aligned to the vertical grid lines on a map, and magnetic north, the direction that a magnetic compass points. This angle is also referred to as magnetic declination.

Understanding Grid Magnetic Angle is crucial for navigation and map reading, as it helps to accurately convert between the grid direction used on maps and the direction indicated by a compass. If a map is oriented with a grid system, knowing this angle allows navigators to adjust their bearings to compensate for the difference between the two types of north when plotting a course or determining their heading.

The other options do not pertain specifically to the concept of Grid Magnetic Angle. Square grid dimensions focus on the physical layout of map grids, vertical measurements relate to elevation rather than direction, and the direction to the sun is unrelated to the magnetic aspects of navigation.