Fig.3 Transition of insolation during summer calorific semester for 65° latitude for northern hemisphere according
to different researchers (Melnikov, Smulsky, 2009): (Milankovich, 1939); b (Brouwer, Van Woerkom, 1950);
c (Sharaf, Budnikova, 1969); d (Berger, Loutre, 1991). X-coordinates axis sets up time in millennia from 1950;
y-coordinates axis sets up: , b, c insolation in equivalent latitudes during the last semester,
d average monthly insolation in July (W/m2).