The Structure of the Solar Granulation

The structure of the solar granulation has been analysed using computer-processed images of two very high resolution (0.25) white light pictures obtained at Pic du Midi Observatory. The narrow range of sizes of granules is not confirmed: on the contrary, it is found that the number of granules increases continuously toward the smaller scales; this means that the solar granulation has no characteristic scale. Nevertheless the solar granules appear to have a vertical size of 1.37, for which drastic changes in the properties of granules occur; in particular the fractal dimension changes at the critical size, which is also the size of the granules providing the largest contribution to the total granule area and radiation. The granules smaller than the critical size could be of turbulent origin.