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.
The erosional landforms produced by continental glaciers are usually less obvious than those created by alpine glaciers. Like alpine glaciers, the movement of continental glaciers followed topographic trends found in the landscape. Continental ice sheets were very thick, between 1000 to 3000 meters.