Fluctuations of photon arrival times in free atmosphere

In this paper we calculate the delay of the arrival times of visible photons on the focal plane of a telescope and its fluctuations as a function of local atmospheric conditions (temperature, pressure, chemical composition, seeing values) and telescope diameter. The aim of this paper is to provide a model for delay-time fluctuations accurate to the picosecond level, as required by several very high time resolution astrophysical applications, such as the comparison of radio and optical data on giant radio bursts from optical pulsars, and Hanbury Brown Twiss Intensity Interferometry with Cerenkov light detectors The results here presented have been calculated for the European Southern Observatory telescopes in Chile (New Technology Telescope (NTT), Very Large Telescope (VLT), European Extremely Large Telescope (E-ELT), but the model can be easily applied to other sites and telescope diameters. Finally, we describe a theoretical mathematical model for calculating the Fried radius through the study of delay-time fluctuations.