Characteristics of intensity spikes in astronomic images have been analyzed theoretically under conditions of the speckle-structure developed due to large-scale turbulent inhomogeneities in the atmosphere. The following parameters were computed: mean area of a spike, density of a spike succession, distance between successive spikes and their volume. It was shown that under such conditions an astronomical image is formed of random diffraction limited images. Intensities of these images are determined by mean intensity of the image as a whole.