This graph shows the output from a scintillometer mounted on the Zodiacal Light Building tower on Haleakala. The scintillometer consists of a diode sensor and electronics to extract both the steady signal (the solar intensity) and the rapid variations of the signal (the scintillation). There is evidence (see, for example, Seykora, Solar Physics 145: 389, 1993; and Coulter, Kuhn and Rimmele, Solar Physics 163: 7, 1996) that there is an inverse correlation between the scintillation and the quality of solar images obtained at the same time.
The red curve plots the solar intensity as a function of time. The detector is mounted in a fixed position, not necessarily vertical, so the intensity curve may not be symmetric about local noon. The blue curve plots the inverse of the scintillation amplitude, in volts RMS, so larger values imply better seeing. Note, however, that the scintillation reading is pretty strongly affected by clouds. When the intensity is varying rapidly, the scintillation data are certain to be of little use.
Previous plots are available in the archive.