As shown in Fig. 2 (A) and (B), the cold season temperature of Japan in some periods changed year by year parallel to the pressure difference between Milano and Haparanda (denoted by ΔP_{M_H} hereafter). The January-February temperature of Irkutsk has a synchronous relation to ΔP_{M_H}, the correlation coefficient being R=0.73, n=53 (1851_??_1936).
In order to find a physical base for the relation between the climates of Europe and Asia, the distribution of the correlation coefficients of ΔP_{M_H} and air temperatures and pressures at various places is investigated, as will be seen in Fig. 8, from which the following facts can be confirmed:
(1) A close and stable correlation is found between the zonal index ΔP_{M_H} and the Jan.-Feb. pressure of high-latitude zone.
(2) A fairly large correlation of ΔP_{M_H} with midwinter temperature can be found between 50°N and 60°N, and in the latitudes higher or lower than that zone, the correlation coefficients tend to rapidly decrease. The longitudinal distribution of the correlation coefficients of ΔP_{M_H} and the temperature is shown in Fig. 6, the part of larger coefficients being in 10°W_??_30°E in West Europe, in 80°E_??_130°E in Central Asia, and the part of smaller coefficients being at about 55°E in North-European Plain.
(3) The line of equi-correlation coefficient (R=-0.8 or R=-0.6) of ΔP_{M_H} and the high-latitude pressure projects exceedingly southward in North-European Plain, where the correlation coefficient of ΔP_{M_H} and the temperature is small. (See Fig. 8.)
From the above mentioned facts the following conclusions can be derived: (a) Though the south-westerly warm air currents, whose mean strength is represented by ΔP_{M_H}, invade into the Arctic air-mass, ascending along the Arctic frontal surface, and weaken the strength of the air-mass as a whole, little or no effects can be exerted upon the air temperature at the earth's surface in the region occupied by the Arctic air-mass.
(b) At the boundary surface between the winds of the Arctic and equatorial air-masses with long wave length of about 90°, warm air intrudes northward between 10°W_??_30°E and 80°E_??_130°E, and cold air projects southward in the vicinity of 55°E. The air temperature in the region of the tongue of warm air correlates with ΔP_{M_H} through two processes, one being the heat quantity transported directly by the prevailing westerlies and the other the strength of cold air currents from the Arctic air-mass whose intensity is controlled by ΔP_{M_H}. The correlation coefficient of the Jan. -Feb. temperature at Upsala is R=+0.73 (1878_??_1926) when C=ΔP_{M_H}, and is R=0.85 (1878_??_1926) when C=σ ΔP_{M_H}-σP_sty (P_sty....pressure at Stykkisholm). In the circulation index C=σΔP_{M_H}-σP_sty, it seems that σΔP_{M_H} represents the heat quantity transported from lower latitudes and σΔP_sty indicates the strength of cold air currents from higher latitudes.