Up to the presen time, the radiation problem mainly attacked on the physical principle in the meteorological works, while it is not always suitable and applicable to the practical uses in the climatology and agricultural schemes which are concerned with atmospheric phenomena over long period. The author has published several papers treated with the problem on the climatological basis. On the present paper he examined the meridional distribution of insolation during the sunarner times. This work consists of two parts, Part 1 is that on the earth without an atnnos-phere and the author calculated the latitude _??_1 where the diurnal amount of insolation for any day takes the maximum and minimum values and the latitude _??_2 where the total amount of insolation during any interval from λ' to λ", λ the celestial longitude of the sun, takes the extreme values. _??_1 is obtained by the differentiation of the fundamental formula of inso-lation and given by
tan_??_=-cot δ cos t0 _??_
where δ is the declination of the sun. The reults obtained are as follows:
_??_
Generally, there exist two maxima, one at the pole on the summer hemisphere and the other on lower latitude, and one minimum. But the maximum at the pole has hardly any significance, because it vanished out en the actual earth covered by the atmosphere. _??_2 is derived from the differentiation of Milankovitch's formulae with _??_ and trafsforzned to the numerical equation of the third degree. Solving the equation the following recults are obtained.
_??_
The results are very interesting, for us and the fact that the most intense heating of the earth's surface during the summer season occurs in the tenfiperate zone from the latitude 30° to 45° and not in the tropical it very important and able to eye pl ain some geographical phenomena. These area:
1) The world's highest temperature on meteorological records exceeds, 50°C and these stationg are all situated within a zone between the latitudes above mentioned (Fig. 1).
2) The s
tations with the extreme maximum temperature higher than 40°C are also foundd in the same zone (Fig. 1 and 2). 3) The most fertile cultivated land with greate_??_t productivity in the world also lies in the same zone.
These are due to the reason that in the tropical regions the amount of radiation varies little through the year in spite of its greater annual amount while in the middle latitudes it is concentrated in a short season in summer exceeding that of the former And that the the temperate regions are not only favoured with their mild climate but also the abundunt solar energy during the growing season lead them to the most prosperous and civilized centers in the world.
