The Botany of Iceland - 01.12.1914, Blaðsíða 96

280
THORODDSEN
February and in the first half of March — 2° to — 4° C., which is
only froni 1° to 3° colder than the average temperature of the
coldest days in ■Copenhagen; but, on the other hand, the warmest
days in Iceland, which occur in the latter half of July and in
August have, on an average, a temperature of only from 7° to 10° C.
There are, however, numerous oscillations from year to year, mostly
during winter, less frequently during summer. The normal tempera-
ture is helow zero (Celsius) from the last days in November to the
íirst days in April, or even May lst on Grímsey. Therefore the Ice-
landic summer is very unfavourable to plant-life, the temperature
being so low during growth-period. The highest mean tempera-
tures for any month fall in July and August and even these reach
onlj' to 11°—I2V20 C. (Papey 8.5° and 9.6°; Vestmannaeyjar 12.7°^
and 12.3°) — the temperature of a mild May or cool September in
Copenhagen. By exception, on some days, the heat may be very
great; the greatest amount of heat registered at Berutjord wTas 26.3° C.,
on Grímsey 26.2° C., at Stykkisholm 22.9° C., and in the Vestmanna-
eyjar 21.2° C. But in the interior of the island — in the valleys —
a higher temperature (27 28° C.) has occasionally been registered.
The lowest temperature registered at Berufjord was — 23.1°, in the
Vestmannaeyjar — 20.9; at Stykkisholm — 26°, and on Grímsey
— 30°.1 At the coast in Iceland the average temperature of the day
and night rarely exceeds 13° C., and at Berufjord there occur, as
a rule, during the year, only four days with such a temperature,
but in Mödrudalur six to seven; a fact which shows among other
things that the summer temperature is often higher in the interior
of the country, while the cold there is also greater during the winter.
On ascending to the interior districts the climate is found to be n»
longer so decidedly oceanic as along the coasls, and the vegetalion
also increases in density the further one proceeds upwards, following
the valleys. Coppice-woods often thrive at the head of valleys in
places where birch - coppices cannot grow out at the coast. The
mean tempei’ature of the coldest day and night in Mödrudalur
was — 29° C., at Berufjord — 19° C. During the period March
6—12, 1892, when the cold was very severe, the mean tempera-
1 All these figures are those for the cold, drift-ice winter 1880—1881. But it
should be mentioned here that the Grímsey station had no maximum thermo-
meter, and that the temperature — 30° C. was one which was registered during
the day. 'In reality the cold had probably been greater, because in the same winter
I noted early in the morning of some days, at Mödruvellir in Hörgárdal a tem-
perature of —32° to —36° C.