A model of a chemical system in which the traveling impulse is affected by externally imposed natural convection in the form of the Benard rolls is considered. The traveling impulse is described by the two-variable model of the B-Z reaction in an excitable regime. Numerical solutions to corresponding reaction-diffusion-convection equations show that the natural convection can generate a train of pulses of excitation, which are created from the single traveling impulse. The subsequently generated pulses spread alternately in the same and in the opposite directions as the initial traveling impulse, and they exhibit some type of translational delayed symmetry.