We present optical observations and 2D hydrodynamic modeling of an isolated shocked ISM cloud. Hα images taken in 1992.6 and 2003.7 of a small optical emission cloud along the southwestern limb of the Cygnus Loop were used to measure positional displacements of ∼ 0. 1 yr for surrounding Balmer dominated emission filaments and 0. 025 − . 055 yr for internal cloud emission features. These measure...
