An active experiment has been conducted in space that allows a test for the theory of nonlinear development of striations in large barium clouds. The results are in excellent agreement with a computer simulation of the E¿B instability reported by Scannapieco et al. (1976). The power law irregularity spectrum predicted by the theory and verified by the experiment is shown here to be due to wave steepening and not to plasma turbulence. The barium cloud results are remarkably similar to bottomside equatorial speed F. A possible role of the E¿B instability in bottomside equatorial spread F is discussed as a supplement to the Rayleigh-Taylor instability during the postsunset rise of the F layer and during anomalous plasma uplifts which occur during geomagnetically active periods.