The force of the wind can literally move mountains. If the mountain is made of sand (or snow) the movement can be observed in a relatively short time. You can make this simple model to show how sand dunes are moved and formed by the wind.
Some safety precautions should be observed during this lab. Slightly moisten the sand so it is not scattered quickly. Always use eye protection (goggles) to prevent blown sand from getting in your eyes. Remember to blow steadily outward through the straw — never suck air in through the straw, especially near the sand.
Sprinkle a thin layer of sand into a shallow pan. Do not smooth the surface entirely. Allow a small rock or stick to sit on top of the sand. Spray a fine mist of water across the top of the sand to prevent excessive movement. Gently blow through the straw or direct the fan toward the sand so it begins to move.
If the straw or fan is held in place and a constant breeze blows on the sand dune, what motion does the dune take? Does part of the dune move faster than other parts? What is the over-all shape of the dune as it travels? Does the wind pattern show protected areas near the dune? How does the size and shape of the dune create unique wind pattern shifts?