Basically, a passive radiator is a reactionary device as the name suggests. When a driver (such as a subwoofer) is mounted to a sealed speaker box (enclosure), the physical forward/back movement of the speaker affects the internal air pressure of the enclosure.
Three landforms created by wind are; sand dunes, yardangs (half-teardrop shaped formations hill sized, and deflation hollows (wind swept depressions.
1 Cliffs are formed when destructive waves attack the bottom of the rock face between high and low water mark. 2  The area under attack is eroded using the major processes of coastal erosion. 3  Points of weakness, such as faults and joints are attacked most, and eventually a wave-cut notch is gouged out.