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 The broadest application of the term erosion embraces the general wearing down and molding of all landforms on Earthâs surface, including the weathering of rock in its original position, the transport of weathered material, and erosion caused by wind action and fluvial, marine, and glacial processes.