We are working on these questions. The stronger the return the more intense is the precipitation. The scale has to be adjusted in winter for snow. Then the scale of the concentric rings on the image usually 40 km apart. Then the date.
Ground clutter is the returns from buildings, mountains, escarpments which are on every image.
Since these features are permanent, they do not move. AP is formed when there is a strong overnight inversion. One sees very strong returns which constantly change size and shape but virtually remains the same place and gradually dissipate. This occurs particularly with clear skies. Registering is free and you can unsubscribe anytime.