From the results of total radiation observed with the Robitzschactinograph at several meteorological stations in Japan, the author of the present paper calculated the constant
a in the formula
Q=
Q0{
a+(1-
a)S/S
0}, proposed by A. Ångström, where
Q is the daily amount of the total radiation observed,
Q0 is the same amount when there is no cloud,
S the observed value of the duration of sun-shine and
S0 its pnssible value. The results of calculation of
a are as follows.
Tokyo 0.22, Nagasaki 0.25, Morioka 0.25 and Mt. Tukuba 0.23.
Further he calculated
a for various kinds of clouds, and he found that
a is 0.40 for upper clouds, 0.35 for middle clouds and 0.22 for lower clouds.
He also found that the total radiation in a clear day in Tokyo can be expressed approximately by the formula:
Q0/
S0=753/
r2 sin
h, where
r is the distance from the earth to the sun measured in unit of its mean distance, and
h the altitude of the sun at the time of the meridian transit; that this expression can be used approximately to the other stations.
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