The Botany of Iceland - 01.12.1930, Qupperneq 16

6
H. M0LHOLM HANSEN
These facts, however, seem merely to apply to conditions either
at the Ievel of the sea, or perhaps only by the coast. If we take a
station like Möðrudalur, situated approximately on a line connecting
Grímsey with Berufjörður, but at an altitude of 480 m above sea level,
this station shows an average of 39 stormy days annually, though
distributed in such a way that the winter has the highest, the summer
the lowest number of stormy days.
Temperature conditions. Above we saw tliat the temperature of
the air near the sea was very closely correlated to the surface tem-
perature of the sea water, but with the addition tliat the tempera-
ture of the sea water was always higher, 1—2° C., than thatofthe
air. In table 1 are shown the average annual and monthly mean
temperatures for South Iceland, West Iceland, East Iceland, and the
highland Möðrudalur. There is a considerable difference between the
coastal stations on the one hand and the highland on the other
hand, a diíference which may also be shown to exist between the
coastal stations mutually.
The mean temperature is highest in South Iceland, being 5.1° C.
at the Vestmannaeyjar. The coldest month here is December with
a mean temperature of 1.2°, the warmest month is July with 10.6°.
The difference belween the coldest and warmest months is 9.4°.
West Iceland, Stykkishólnnir, has a mean annual temperature of 2.8°,
the coldest month, February, registering a mean temperature of 2.7°
below zero, the warmest month (July) 9.7°, with a diíl'erence of 12.4°.
Berufjörður in the east country has the same mean annual tem-
perature, 2.3°; here March is the coldest month, 1.7° below zero,
July the warmest, 8.5°, and the difference between the coldest and
warmest montlis is somewhat less, 10.2°.
Grímsey, in the north country, has a mean annual temperature
of 1.5°, a mean temperature for March of 3.6° below zero, for July
of 7.0°, difference 10.6°.
The highland is considerably colder. The mean annual tem-
perature for Möðrudalur is 0.2° below zero, the January temperature,
7.2° below zero, the July temperature 10.0°. The difference, 17.2°,
is thus considerably greater than that of the coastal stations.
The number of frosly days is closely correlated to the tempe-
rature conditions. The smallest number is recorded from South
Iceland which shows an average of 109 per annum. Grímsey has
the greatest number, 192. Berufjörður lies belween these two extremes
with 158 frosty days and Stykkishólmnr with 166 frosty days. Un-