  The solar radiation are electromagnetic waves, composed of infrared, visible
spectrum and ultraviolet. The infrared component is the cause of thermal
energy, the visible spectrum allows to see and the ultraviolet component is the
most energetic part and dangerous for the human body (skin and eyes). The
ultraviolet rays are divided in a wavelength range, in three parts; called UVA
(100-280 nm), UVB (280-315 nm) and UVC (315-400 nm). The UVC are the most
energetic (followed by the UVB rays ), however are stopped in the ozone layer.
In this work it shown a statistical analysis of the UVB index measured by five
station in Mexico City, from the years 2000 to 2022. Through a Gaussian fit
distribution, it was found that the range when the IUVB value exceeds the value
of seven, which is from 11:00 to 16:00, having an average mean value of 13:09
hrs. $\pm$ 4 min. i.e. the time at which the UVB index reaches its maximum
value. This occurs in the months from February to October. More than 80% of
radiation is for UVB values less than 7 and less than the remaining 20% is for
IUVB values greater than 7. Finally, it was possible to observe that the mean
value per year, reaches its maximum when the solar cycles occurs, which was in
the years 2003 and 2013.
