Low frequency electrostatic fluctuations (&ohgr;<&OHgr;i) travelling in E¿B direction are observed in a laboratory plasma simulating conditions similar to night time equatorial F-region. The density and potential fluctuations in the region of the plasma where effective g parallel to density gradient ∇n has similar spectral characteristics to that of the results of our earlier experiment of bottom side of equatorial spread F. The k-spectrum of density in this region of plasma exhibits two marked slopes with indices n=-2.5¿0.3 and -4.6¿0.3 where as the potential spectrum exhibits one slope with index -5.2¿0.2. The fluctuations are generated in the region where ∇n is antiparallel to g and appear in the other region due E¿B motion. Results are in agreement with in-situ measurements in F-region, theoretical predictions and numerical simulation of Rayleigh-Taylor and drift wave instabilities. ¿ American Geophysical Union 1992