  Using irradiance and temperature measurements obtained at the Facultad
Regional San Nicol\'as of UTN, we performed a preliminary study of the linear
relationship between monthly averaged daily solar radiation and daily thermal
amplitude. The results show a very satisfactory adjustment (R = 0.848, RMS =
0.066, RMS% = 9.690 %), even taking into account the limited number of months
(36). Thus, we have a formula of predictive nature, capable of estimating mean
monthly solar radiation for various applications. We expect to have new data
sets to expand and improve the statistical significance of these results.
