THE INFLUENCE OF GEOGRAPHICAL LATITUDE ON THE ANNUAL DYNAMICS OF THE PHOTOPERIODIC COEFFICIENT

The article presents data on annual variations and the level of the photoperiodic latitudinal coefficient on the territory of Russia, which must be used to calculate corrections during transverse and longitudinal studies. For comparative analysis, the cities of Russia were selected, located on the territory from 73o to 42oN.S. and distributed by longitude from 20o to 137oE.W., divided into 4 groups: ~60o; ~55o; ~50o; ~40oN. S. and the cities of Russia located beyond the Arctic Circle. The presence of the annual dynamics of the photoperiodic latitudinal coefficient implies the introduction of corrections during seasonal longitudinal studies. Simultaneous inter-latitude studies, in order to level the geographical and seasonal features of the light regime, it is advisable to carry out during the autumn and spring equinoxes, when the photoperiodic latitude coefficient is zero. The change in the duration of daylight during a trans-latitude flight within the borders of the Russian Federation is up to 9 hours, which can induce photodesynchronosis or latitudinal jetlag. © 2025 Elsevier B.V., All rights reserved.