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.
Wind carried sediment falls to the ground when the wind slows down. Deposits formed by wind erosion and deposition include sand dunes and loess deposits. Sand dunes have coarse grained sediments, loess has finer sediments, both are caused by wind erosion.