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.
Erosional Landform Pictures. There are different ways to classify landforms, but there are three general categories: landforms that are built (depositional), landforms that are carved (erosional), and landforms that are made by movements of the Earth's crust (tectonic). Here are the most common erosional landforms. This arch, in Arches National Park in Utah, formed by erosion of solid rock. Water is the sculptor, even in deserts like the high Colorado Plateau. Rainfall acts in two ways to erode rock into an arch.