Náttúrufræðingurinn - 1956, Side 13

HEILDARGEISLUN SÓLAR í REYKJAVÍK
75
3. Geiger, R. 1950. The Climate near the Ground. Harvard Univ. Press,
Mass.
4. Hand, I. F. 1949. Weekly mean values of the daily total solar and sky
radiation. U. S. Weather Bureau. Technical paper II.
5. Lunelund, H. 1934. Contribution to the Knowledge of Solar Radiation
in Finland. Societas Scientiarum Fennica, Helsinki.
6. Mörikofer, W. 1940. Meteorologisclie Strahlungs- und Messmethoden íur
biologische und ökologische Untersuchungen. Bericht iiber das Geo-
botanische Forschungsinstitut Riibel in Ziirich fiir das Jahr 1939. Ziirich.
SUMMARY
Total solar and sky radiation in Reykjavík
by Iijarni Helgason.
Studies of total solar and sky radiation in Reykjavík, SW-Iceland, are now
being done for the first time. The study began in July 1954 and since then
daily measurements have been done with the aid of a destillation luzimeter
of the „Bellani“-type, obtained from the Physical-Meteorological Observa-
torium in Davos, Switzerland, tlie instrumental error of which does not ex-
ceed 3% of the total.
It has generally been believed, that high values of radiation occurred in
Iceland, because of its clear summernights and duration of „light". However
according to observations done during the two previous summers the radiation
received in Reykjavík did not exceed a niaximum average of 0,25 cal/cm2/min,
which seems to be a much less radiation than is received by otlier places of
similar latitude on the northern hemisphere.
On table I, showing the monthly total radiation and daily mean values in
cal/cm2, one will notice the great difference between the first ltalf ancl the
second half of the year 1955. One also notices, that May 1955 has about 100
calories higher daily mean radiation than the following June. The difference
between the second halves of the years 1954 and 1955 is also noteworthy,
since September 1954 has twice as much radiation as September 1955 and in
December 1954 the radiation is fourfold as compared with that of December
1955.
The first graph (1. mynd) — monthly average intensity calculated as cal/-
cm2/min — shows the interesting fact, that the intensity is not greatest during
the summer months, but in spring and autumn. Maximum average intensity
of 0,25 cal/cm2/min occurrecl in May 1955 ancl then 0,23 cal/cm2/min in
September 1954.
However radiation of 0,48 cal/cm2/min occurred on the 21st of March
1955 and then of 0,42 cal/cm2/min on the 2nd of June 1955. The 24th of
November had tlie lowest radiation at the rate of 0,003 cal/cm2/min.
A comparison with other meteorological factors as shown on graplis 2, 3,