Page "Radar" Paragraph 76

Clutter is detected and neutralized in several ways.

Clutter tends to appear static between radar scans ; on subsequent scan echoes, desirable targets will appear to move, and all stationary echoes can be eliminated.

Sea clutter can be reduced by using horizontal polarization, while rain is reduced with circular polarization ( note that meteorological radars wish for the opposite effect, therefore using linear polarization to detect precipitation ).

Other methods attempt to increase the signal-to-clutter ratio.