CONTBIBUTIONS TO THE NATUBAL HISTOBY OF ALASKA. 29 



Frost spiculse attain a length, of 2 inches during a temperature between zero and melting- 

 point of ice and a light southwest wind. These grow on all objects, though on posts, palings, 

 feathers and hairs the most beautiful needles are formed. They are generally broken off by 

 a succeeding wind. 



The results obtained from measurements of snow have been very much less than the actual 

 amount. No sooner does a snow begin to fall than a wind will drift it into the sea or interior. 

 The annual fall is probably not one-half so great on this part of the coast as it is in the interior 

 but few miles. 



I estimate that only about three-fifths of the true amount has been recorded, so deficient have 

 been the snow measurements. It has a range of seventy degrees of temperature for falling. 

 Large flakes, almost snow-balls, have fallen when the exposed thermometer read 40°, and the 

 lowest has been— 30°. 



The greater amount of snow falls in March, and as this mouth is the windiest, it is very 

 evident that the foregoing statement may be correct. I estimate, roughly of course, that the 

 snow-fall of winter is fully one-third greater than the rain-fall for summer. 

 « 



DEW. 



Dew is not often noticed, probably from the fact of the short nights during the period 

 that dew should fall. It is most often noticed in August and September, sometimes forming 

 copiously. 



FOG. 



Fog is rare in winter and more common in summer, as often the result of the low descent of 

 clouds as to the effect of the intermingling of two currents of air having different temperatures. 

 Fog-patches are often seen on the low grounds. A general fog attends the breaking up of the ice 

 in spring, and is said to be an index to the breaking up of the ice in the Yukon Biver. On two 

 occasions this has been verified. 



The fog-cloud seldom- lasts longer than a day, still more often for only a few hours, though 

 intervals of more or less density have prevailed for two or three days. A wind backing to the 

 southwest after a warm spell usually produces the most persistent fog. 



CLOUDS. 



Situated as this part of the country is, and partaking the nature of both a marine and con- 

 tinental climate, the amount of cloudiness is not so great, after taking an extended period into 

 consideration. 



The proportion of cloudiness is taken at 2 p. m. ; about equal to the amount of clear and fair 

 days taken at the same hour of the day. 



From June to November the amount of entire cloudiness consumes about two-thirds of the 

 time. 



From November to March the number of clear days equal at least those of cloudy, while fair 

 days are proportionate equally to either. 



The ratio of clear to cloudy is one to three, while fair stands two to three. To be plainer, one 

 day in six is clear, two fair and three cloudy, when taken for an extended period. 



The greatest number of clear days occur in November and February ; the latter somewhat in 

 excess of the former month. 



STRATUS. 



I have divided the stratus cloud according to its apparent height by a qualifying word. 



This cloud, usually low or at a medium height, presents its characteristic color. Variability 

 of color is recorded whenever occurring. 



Sometimes in moderate weather the color assumes the deepest blue-black, having this color 

 more intensely than in any other form of cloud. 



Stratus prevails to a greater extent than any other cloud, often continuing for nearly a month 



