20 H. MOHN. METEOROLOGY. [NORW. POL. EXP. 



CLOUDS. 



The amount of cloud is given according to the usual scale : = clear, 

 no clouds, blue sky, to 10 = entirely overcast. Thin clouds are indicated 

 by as exponent, very thick clouds by 2 as exponent. 



The forms of the clouds were noted in conformance with HOWARD'S 

 definition. The International Cloud Atlas was not published at the time of 

 the departure of the Expedition in 1893. 



The drift of the clouds is given by noting the point of the compass 

 from which they came. 



PRECIPITATION. STATE OF THE SKY. 



The Expedition had a rain-gauge and a snow-gauge of the same pattern 

 as those of the Norwegian Meteorological Institute. The rain-gauge has a cir- 

 cular, and the snow-gauge a square, receiving surface of 225 square centi- 

 metres. The gauges were placed on board or on the ice. The amount of 

 precipitation collected in the gauges was always very small, and cannot be 

 regarded as a true measure of the quantity of liquid or frozen moisture that 

 fell upon the ground. It is a well-established fact that it is impossible with 

 ordinary gauges to obtain the full amount of rain, and particularly of snow, 

 measured in the conditions prevailing in arctic regions. The amount of pre- 

 cipitation noted has therefore not been entered in the Tables in a special 

 column, but has been transferred to the remarks and to a special Table. 



The weather and the state of the sky are given in the Tables by the 

 conventional signs and the "Beaufort Notation". 



Rain. * Slight sleet. 



Slight rain. * 2 Heavy sleet. 

 2 Heavy rain. A Hail. 



* Snow. = Fog. 



* Slight snow. = Foggy rain. 



* 2 Heavy snow. Hoar-frost. 



* Sleet. - - Rainbow. 



