Some peculiarities of the formation of the spectral behavior of the aerosol optical depth are discussed. It is shown that the observed variety of spectral behaviors t(l) is formed due to variations in the optical effect of, at least, three aerosol fractions: accumulative, intermediate dispersed (ID), and specific coarse. Each of the aforementioned fractions has its peculiar rhythm of development and response to the diurnal variations of meteorological quantities. According to data obtained, optical manifestation of the accumulative fraction reacts not only on the change of temperature and relative humidity, but also its behavior agrees with the columnar water vapor of the atmosphere. It is revealed that the narrow mode of intermediate dispersed fraction is characteristic of not only clean arctic air, but it is also observed in the columnar mean size spectrum, under ordinary conditions. Diurnal variations of the ID fraction in the atmospheric column are an evidence of the presence of maximum near noon. Correlated dynamics of the variations of second and third modes shows a stable diurnal circulation of the ID-fraction particles inside the atmospheric column and a change of their size.