699 



and according to observations diiring 25 years the lowest tempe- 

 rature is — 11,6*', the highest 21,2°, but these extremes are verj^ 

 rare and on the whole of very short duration when they occur. 

 Thus it is evident, that the temperature of the Færoes is rela- 

 tively high in winter, low in summer, and very uniform all the 

 year round. It is of course the direct influence of the sun that is 

 of special importance to the algæ, and on hot, sunshiny days the 

 amount of heat and consequently the evaporation and drying in- 

 crease considerably. But days of really hot sunshine are as a rule 

 few, (the Færoes have no so-called summer days, according to 

 Willaume-Jantzen); moreover, the sun's warmth acts directly, 

 as a rule, for but a short period and is soon replaced by rain, fogs 

 or clouds, so that the danger of the algæ on the Færoese coasts 

 being exposed to high temperature and consequently to evaporation 

 is greatly diminished. 



The amount of humidity in the air is rather high in the 

 Færoes; for the whole year it is 82, in summer a little more, 

 about 8o, in spring a little less, about 80. Deviations naturally 

 may occur, but are generally of short duration. 



The very uniform and low mean temperature of the air to- 

 gether with the high degree of humidity, both varying but a little 

 from the normal, are certainly of great importance to the littoral 

 algal vegetation, the very luxuriant growth of which is certainly due 

 for the most part to these conditions. This view has partly also 

 been put forward by Si m mons (75). On page 263, he writes: »Das 

 Auftreten vieler Arten in weit hoherem Niveau als sonst, kann 

 deshalb, was die fåroische (und wohl auch Nordlands) Algenvege- 

 tation betrifft, nur oder wenigstens am besten durch die Temperatur- 

 verhåltnisse erklårt werden.« In addition to the temperature, the 

 little direct sunshine, the weaker light on the whole, the humid 

 air with much rain and fog, and especially the rough sea are 

 naturally likewise imporlant factors. 



e. Light. 



The climate of the Færoes is, as already mentioned, rich 

 in fogs, rain, and cloudy weather, and on the other hånd rather 

 wanting in sunshine. According to Willaume-Jantzen, the 

 amount of clouds at Thorshavn is 7,4 (O = clear sky; 10 = over- 

 cast); and the Færoes have in all 178 »cloudy days«, that is, 



Botany of the Færoes. 45 



