CONTRIBUTIONS TO THE NATURAL HISTORY OF ALASKA. 31 



CIRRI. 



The prevailing forms of this cloud are pencil-streaks and whirls. Many modifications occur, 

 which bring the cirri and cirro-cumulus in such close relationship that it is often a matter of nice 

 discrimination to separate them. In this condition they are recorded as intermixed. This condi- 

 tion may continue for several days with not another cloud to be seen, and calm to gentle surface- 

 currents, while the two clouds are being rapidly hurled from north to south, or, more commonly, 

 vice versa. 



Above this intermixture and the upper limits of the cirri are multitudinous modifications of 

 the primary cirri. Among these the principal varieties are jelly-fish (usually head to the wind), 

 horsetails (rare), wisps, plumes, and filoplumate curls, pectinate and double pectinate; forms like 

 the blur of a moderately-stretched cord having locks of loose cotton closely arranged on it and the 

 string put in motion with a twang of the finger. This appears to be the pencil and curl cloud 

 interformed. 



Many other varieties, such as the fancy can suggest, are also seen. The cirro-cumuli and cirri 

 in this latitude presents such attractive forms that the pen cannot describe and only the most 

 skillful brush portray. 



Pale, scarcely distinguishable cirri rapidly form the frayed curl cloud, descend through the 

 cirro-cumulus region, seem to miss the cirro-stratus, and form stratus in such a short time that it 

 is hardly credible. Rain in the summer or snow in winter is sure to result from this rapid descent. 



SUNSET SHADOWS. 



Sunset shadows are seldom seen, and more rarely perfect. On one occasion eleven perfect 

 bands or fingers were seen to point to the zenith when the sun was within 2 degrees of setting. 



CLEAR WEATHER. 



The sky is often clear of clouds for days at a time, especially in the mouths of November and 

 February ; clear days occur rarely in the summer, and are then pleasant in the extreme. 



I have entered only absolutely clear weather as clear, or with such few exceptions as will 

 readily show themselves. 



WINDS. 



In the earlier months of my stay at this station I recorded the winds in their subdivisions of 

 the eight principal poiuts of the compass, but later I have disregarded this on account of the 

 extreme unsteadiness of all winds. 



The oscillations of the vane are extremely rapid, and covering on one occasion a range of 180 

 degrees, while the usual swing is 15 to 80 degrees, 45 being common; steadiness of the vane being 

 very rare, and then only in light to fresh winds. 



SURF ACE-CURRENTS. 



North wind. — This wind prevailing in the southwest and westerly quadrants of storms, has a 

 general tendency to veer, and often, by its extreme unsteadiness, oscillates from north 18° degrees 

 W. to NNE., or even to ENE. It blows for days together without a sign of cloud. Its velocity 

 is extremely variable, from light breeze to a terrific hurricane. 



In October it blows for weeks at a rate of from 15 to 70 miles per hour, while for the other 

 seasons its average rate is about 34 miles. During the prevalence of this wind fair to clear 

 weather obtains. This wind is taken as the standard for relative frequency, and will be considered 

 as the unit of ratio. 



The temperature of this wind is low. 



Northeast wind. — The northeast current so nearly resembles that of the north that to separate 

 them is more convenient than advisable. The oscillations of the vane, during high winds from this 

 point, cover two-thirds of the oscillations for the north wind, besides having its own tendency to 

 eastward. Its velocity is usually about 31 miles, and ranges from light to highest storm-rate. 



