Diffusion of a cloud emitted by a pulsed source was studied in field and numerical experiments. The field experiment was conducted in summer in steppe with the use of remote and local monitoring instrumentation. A source emitting the cloud was modeled by a charge with an indicator substance set off at the height of 10 m. The cloud formed of the condensed-phase products of explosion was monitored with a scanning lidar. The ratio of the backscattering signal from the cloud to the signal from the background aerosol, as well as the time and coordinates of sensing points, was recorded. At the distance of 25-30 m from the site of explosion, an ultrasonic meteorological station measured the air temperature, vertical and horizontal components of the wind speed and its direction, total energy of turbulent motions, the level of tangential turbulent friction stress, and vertical turbulent heat flux. The experimental lidar data were compared with the results of numerical simulation of the spatial distribution of the pollutant using the statistic Gaussian distribution model. The calculated results as a whole are in a close agreement with the experiment.