Surface Clutter – Ground or sea returns are typical surface clutter.
Returns from geographical land masses are generally stationary, however, the effect of wind on trees etc means that the target can introduce a Doppler Shift to the radar return. This Doppler shift is an important method of removing unwanted signals in the signal processing part of a radar system. Clutter returned from the sea generally also has movement associated with the waves.
Volume Clutter – Weather or chaff are typical volume clutter.
In the air, the most significant problem is weather clutter. This can be produced from rain or snow and can have a significant Doppler content.
Point Clutter – Birds, windmills and individual tall buildings are typical point clutter and are not extended in nature. Moving point clutter is sometimes described as angels. Birds and insects produce clutter, which can be very difficult to remove because the characteristics are very much like aircraft.