Radial/radar graphs are sometimes called rose charts. They have a central point from which data radiates outwards.
Data can be plotted as points along a line, where all points are joined up to form a shape. It could also be plotted as segments along a line. Wind speed and direction is often shown as a radial graph. Radial graphs can show lots of different data and do not have to involve compass points.
When interpreting radial graphs, you should include:
NB: When interpreting data in any graph, table or diagram you must describe them fully and quote figures to back up your point.