Some parameters for describing optical qualities of a short-term beam pattern of a collimated laser beam propagating through a turbulent atmosphere are evaluated for a series of numerically-generated patterns. These parameters include the on-axis, peak, and energy Strehl ratios and the sharpness. Their statistical characteristics are analyzed and the validity of these parameters for describing optical qualities of the beam pattern is discussed. Main results could be summarized as follows. The energy Strehl ratio could reflect the energy concentration of the whole beam; the sharpness well reflects the energy concentration in a local area, and could be used for describing the optical quality of laser beam in the turbulence. Generally the turbulence is benefit for promoting the pattern sharpness.