Refer to figure.
Aeronautical charts attempt to convey the world on a flat piece of paper, but to do this perfectly is impossible, and so they attempt to maintain a few key elements. Two of the characteristics that the lambert conformal conic chart aims to maintain are scale and convergency.

The Lambert Conformal Conic chart is a nautical chart type that is set up to be most useful at the mid latitudes, and it has a "parallel of origin", where the convergency of the chart is the same as the convergency of the Earth, and therefore, at that parallel of latitude, a great circle on the Earth is a straight line. Either side of this line, however, the Earth's convergency changes, but the chart convergency, being a flat piece of paper, does not.

A Lambert's chart is constructed from a cone which is placed in a way that cuts through the Earth slightly - as such it intersects the Earth surface at two points, known as Standard Parallels. This is done so that the scale of the chart can be within 1% accuracy of the quoted scale (for example 1:500 000), over a much larger region.

The Scale of a Lambert conformal chart is only perfectly correct along the standard parallels, so in this case, 45°N and 58°N.

Part of the chart (outside the Standard Parallels) is outside the Earth and part (between the Standard Parallels) is inside the Earth. The part inside the Earth (between the standard parallels) has a scale smaller than the quoted scale (up to 1% different), and the outside section has a larger scale (up to 1% different). This rule of 1% sets the limit for how large a projection can be.