44 H. JONSSON 



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 

 algae w r ill 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. Berufjordur (23 years) 77 78 81 80 



N. Icel. Grimsey (21 years) 83 83 85 86 



SW. Icel. Stykkisholmur (20-23 years) . 88 85 83 86 



S. Icel. Vestmannaeyjar (12 years) 81 79 82 81 



As a comparison with the Faeroes might be of interest, the 

 figures showing the mean humidity as percentages at Thorshavn 

 Willaume-Jantzen, I.e.) are appended. 



Winter Spring Summer Autumn 



Thorshavn in the Faeroes (25 years). .81 79 84 84 



From these figures it appears that the humidity of the air in 

 Berufjordur is less than in the Faeroes while the humidity of the 

 air at Grimsey and also at Stykkisholmur is greater than in the 

 Faeroes. The humidity of the air in the \vinter and the spring in 

 the Vestmannaeyjar and in the Faeroes 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. Precipitation. 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 Faeroes (Wil- 

 laume-Jantzen, 1. c). 



Winter Spring Summer Autumn The year 



E. Icel. Berufjordur (23 years). .. 348.0 222.7 203.7 340.3 1114.7 



N. Icel. Grimsey (16-22 years). .. 83.5 64.8 85.6 139.9 373.8 



SW. Icel. Stykkisholmur (1 8-22 yrs.) 191.5 115.2 113.6 203.8 624.1 



S. Icel. Vestmannaeyjar (15 years). . 354.1 257.3 252.1 402.2 1265.7 



Thorshavn in the Fseroes (25 yrs.). 510.9 485.2 272.4 324.6 1593.1 



