The Botany of Iceland - 01.12.1914, Síða 106

290
THORODDSEN
inhabited districts, because there alone permanent meteorological
stations are found. The climate of the uninhabited plateau is far
less known. Although it is possible, from the climate at the coast,
to draw fairly definite conclusions as regards the climate of the
interior, derived from the height above sea-level and the distance
from the coast, yet almost all accurate investigations and observa-
tions from the plateau are wanting. The only climatological station
on the plateau is Möðrudalur (469 metres above sea-level), and it
will be seen that the climate there is far more severe than at the
coast (see Table IV), from which again may be concluded how.very
severe must be the winter up at the Jökulls in the centre of the
island, at a height of 1000—1400 metres; the climate in the interior
is Certainly far more continental than at the coast. The winter in
Möðrudalur (mean temperature — 7.20 C.) is almost twice as severe
as in the inhabited districts of North Iceland at any height up to
100 metres above sea-level, with a mean temperature of — 3.5° C.
The spring of Möðrudalur is very cold with a mean temperature
of — 2.1° C., and the mean autumn temperature is also below
zero (— 0.7° C.), but the summer is as warm as at the coast. On
Odádahraun and north of Arnarfellsjökull the winter is beyond
doubt very severe, with perhaps a mean temperature of — 10°
or less. That the frost persists for a long time is seen by a few
small oases, where the snow does not thaw until during July and
where a miserable vegetation appears only for a period of two
months. On the plateau the storms blow with great force, driving
sand, gravel and small rock-fragments across the desolate plains
and ridges of rock, thereby striating and polishing them; as men-
tioned above, the wind also carries great quantities of tuff-dust and
blown sand l'rom the plateau down to the valleys and lowlands.
During summer it may sometimes become fairly warm in the middle
of the day, but, in the interior of the plateau, it usually freezes
during the night, so that small water-courses and pools of water
are ice-covered early in the morning. Snow-storms occur now and
then, and sand- and rain-storms and fogs are very common. The
large Jökull-domes in tlie centre of the plateau often appear to
form a climatic boundary, the weather frequently being opposite
in character to the north and south of them. Thus, there is often
bright sunshine on Arnarvatnsheiði, north of Langjökull, while south-
easterly storms of rain are raging over the plateau south of the
same Jökull; conversely it may be warm sunshiny weather on the