The videos assume that all communication is via the great-circle short path route and include only inter-zone contacts. For the CQWW contests, there is one node (i.e., the end of an arc) located in each of the 40 CQ zones. The width of the arcs is an absolute measure of the number of QSOs taking place over that path in the particular 10-minute segment. The colour of the arc reflects the relative number of QSOs taking place over the path. Each separate still image (i.e., 10-minute segment) is normalized so that the path with the greatest number of QSOs is rendered in white. Paths with fewer QSOs are in progressively darker colours.
Thus, arc colour should not be compared from one still image to another; arc width, however, is meaningful. The width of an arc in pixels is one plus the natural logarithm of the number of QSOs represented by the arc.