The Botany of Iceland - 01.12.1930, Blaðsíða 15

STUDIES ON THE VEGETATION OF ICELAND
5
tember, and we íind also, that only on the south and west coasts
is the temperature of the air, on the average, always lower tlian
that of the sea water, whereas on both north and east tlie teinpe-
rature of the air niay remain for months higher than that of the
sea water, this being especially the case on the east coast.
The Polar Current carries with it great masses of ice. This
current of ice can either strike Langanes or the east coast of Vest-
íirðir, south of Cape Horn. If it strikes Vestfirðir, then it is borne
by the eastward going current along the north coast, rounding
Langanes and drifting on along the east, sometimes even also along
the south coast, unlil all the ice has melted or disappeared out into
the Atlantic. Wlien the current of ice strikes Langanes or Melrakka-
sljetta, it is carried out into the Atlantic by the same current. The
quantity of drift ice varies to an extraordinary degree; in some years
there may be none at all, while in others, “ice years”, it may lie
about until far on in summer. The result is seen in great climatic
flucluations.
The winds in Iceland are determined by two centres of low
barometric pressure, one lying south-west of Iceland, and another,
minor one, situated towards the north-east. The former constitutes
the principal factor in determining the state of the wind, and in
consequence, easterly winds are most prevalent, especially on the
west. In East Iceland, the eastern minimum is of no slight im-
portance, westerly winds being here of more frequent occurrence
Ihan in other parts of the country.
The highest frequency percentage for calm occurs in summer,
and this applies to all parts of the country; the highest percentage
is recorded from the Vestmannaeyjar, with an average value of 22,
a percentage of calm in winter of 10—20 and in summer of 25—30.
At Grimsey the percentage of calrn is lowest, on an average ahout
10, 4—6 in winter, 16—19 in summer. East and West Iceland show
somewhat similar conditions, though in winter the percentage is
higher, about 10.
The number of stormy days is closely correlated to this (see
table 1). It applies to all parts of tlie country that the number is
higliest in winter, lowest in summer. It is, however, very variable.
It storms most frequently in the south-west and soutli. Thus Stykkis-
hólmur has, on an average, 50 stormy days per annum, the Veslmanna-
eyjar 25. The number is considerably less for the nortli and east.
Grímsey has 11, Berufjörður only 8 stormy days annually.