The Botany of Iceland - 01.12.1912, Blaðsíða 58

44
H. JÓNSSON
consequently the damage which the ice causes is not noticeable in
the long run, it is noticed chiefly in the same year or the year
following, and is remedied comparatively quickly.
B. The Humidity.
Very great importance must be ascribed to this as regards the
algal vegetation left exposed. During the period of desiccation there
is always the danger of the evaporation becoming too great, espe-
cially if the air is dry. The more humid the air, the better the
algæ will be able to maintain life in it. The following figures from
four places, each situated on a different part of the coast, show the
mean humidity of the air as percentages (Willaume-Jantzen
1. c.).
Winter Spring Summer Autumn
E. Icel. Berufjörður (23 years) 77 78 81 80
N. Icel. Grímsey (21 years) 83 83 85 86
SW. Icel. Stykkishólmur (20-23 years) . 88 85 83 86
S. Icel. Vestmannaeyjar (12 years) .... 81 79 82 81
As a comparison with the Færöes might be of interest, the
figures showing the mean humidity as percentages at Thorshavn
Willaume-Jantzen, 1. c.) are appended.
Winter Spring Summer Autumn
Thorshavn in the Færöes (25 years).. 81 79 84 84
From these figures it appears that the humiditv of the air in
Berufjörður is less than in the Færöes while the humidity of the
air at Grímsey and also at Stykkishólmur is greater than in the
Færöes. The humidity of the air in the winter and the spring in
the Vestmannaeyjar and in the Færöes is the same, while at the
latter place it is a little greater in the summer and autumn.
C. Precipitation, Amount of Cloud, Foggy days, Wet days.
a. P recipitation. The following figures show for purposes
of comparison the mean downfall in millimetres at four places in
Iceland, one on each coast, and at Thorshavn in the Færöes (Wil-
laume-Jantzen, 1. c).
Winter Spring Summer Autumn The year
E. Icel. Berufjörður (23 years). .. 348.0 222.7 203.7 340.3 1114.7
N. Icel. Grímsey (16-22 j'éars). . . 83.5 64.8 85.6 139.9 373.8
SW. Icel. Stykkishólmur(18-22 yrs.) 191.5 115.2 113.6 203.8 624.1
S. Icel. Vestmannaeyjar (lðyears). . 354.1 257.3 252.1 402.2 1265.7
Thorshavn in the Færöes (25 yrs.). 510.9 485.2 272.4 324.6 1593.1