  Long-term series of measurement of spectral transparency of the atmosphere
(\lambda = 430 nm) and atmospheric optical thickness (AOT) measured by
multimode photometer CE 318 in the region of Yakutsk array are analyzed.
Correlation of AOT with intensity of air showers with small energies 10^{15} -
10^{16} eV is found. The variability of aerosol composition of the atmosphere
during the registration period of the Cherenkov light should be taken into
account since it may affect the quality of determining characteristics of air
showers.
