Debris clouds generated in hypervelocity tests using various thicknesses, 2A12 aluminum plates named "bumper", and 6.35-mm-diameter, 2017 aluminum spheres are presented and described. Impact velocities for these tests were between 2.23 km/s and 5.26 km/s. The morphological features such as components and shape, and the formation process of the debris clouds were discussed and compared with those presented by Piekutowski. As a result, the front element of debris cloud observed by Piekutowski was not evident in views of the debris clouds in this paper. A certain value of t/D ratio (bumper thickness to sphere diameter ratio), at two sides of which, the formation process of the internal structure of the debris cloud were different existed. The distance between the external bubble and the primary element decreased as the t/D increased regardless of impact velocity. The size and number of fragments in the debris clouds were not evaluated quantitatively, but described qualitatively.