differences at the various polar stations. In the winter of 1941-1942, Somov successfully traced 

 the wind drift of ice masses in the White Sea, using both my laws and my coefficients. 



The following may serve as an example of the possibilities of employing my method. On 27 

 March 1943, during a flight north of Rudolf Island (Franz Joseph Land), the navigator of the plane 

 Padalka reported that dozens of icebergs were sighted between 84° and 84° 30' north, the number 

 of icebergs decreased westward. However, in 1937, during several flights not a single iceberg 

 was seen in that region and in general no icebergs were sighted on the meridian of Rudolf Island 

 (Ostrov Rudol'fa) thus the question arises: from where did the icebergs come? 



At my request and upon my suggestions, Karelin solved the problem by the "reverse 

 approach, " namely: knowing the end point, he calculated the initial point on the isobar charts. 

 He found that the icebergs were brought from the west coast of Severnaya Zemlya. In his calcula- 

 tions, Karelin did not consider the steady surface current which carried the Fram and the Sedov 

 from east to west. If he had done this, undoubtedly his calculations would have shown that these 

 icebergs were brought from regions adjacent to the east coast of Severnaya Zemlya, where large 

 accumulations of icebergs are observed some years. 



LITERATURE: 67, 70, 72, 77. 



Section 138. The Drift of Ice During the Passage 

 of Pressure Systems* 



During the passage of pressure systems, the wind at one in the same point on the earth's 

 surface changes speed and direction continually. In this connection, the wind drift of ice also 

 changes correspondingly. The cyclone is the most sharply defined pressure system. Let us 

 examine the influence of the passage of a cyclone on the movement of ice in the northern hemi- 

 sphere, and let us make the following simplifying assumptions: 



1. The isobars in the cyclone are circular. 



2. The ice drifts along the isobars at a velocity proportional to the pressure gradient. 



3. The ice floes are free to move in any direction and have no inertia (they begin to drift 

 soon after they enter the cyclone region and they stop drifting as soon as they leave this region). 



Figure 136 shows the drifts of ice floes which are equidistant at the initial moment of drift 

 and on a line perpendicular to the cyclonic motion. The pressure is the same throughout the 

 cyclone region. The cyclone is moving at a constant speed. The drift speed of the ice floes is 

 assumed to be 1/25, l/lO, 1/5 and 1/2 of the rate of movement of the cyclone. 



Figure 137 shows a more complex case. It is assumed that the pressure gradient in the 

 cyclone region varies according to the law depicted in this figure. The speed of the ice floe drift, 

 varying according to this same law, becomes so small at a certain distance from the center of the 

 cyclone that in practic it can be neglected. 



Figure 138 shows the curvature of the lines parallel and perpendicular to the path of the 

 cyclone and equidistant at the initial moment. It is proposed that the isobars of the cyclone are 



♦This section was written after the book had been submitted to the printer, thus, not all the 

 conclusions were reached which might have been reached in a more thorough treatment and the 

 conclusions reached were not formulated precisely. 



377 



