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.
Landforms of erosion. Headlands and bays. Headlands and bays most commonly form along discordant coastlines. Discordant coastlines form where geology alternates between bands of hard and soft rock (see image below). As soft rock, such as glacial till, is more susceptible to erosion it erodes more rapidly than more resistant rock such as chalk. This results in the formation of headlands and bays. Bays and headlands along a discordant coastline.