PATH OF THE 



CYCLONE CENTER 



Figure 138. Curvatures of lines perpendicular and parallel to the 

 path of the cyclone. 



2. All floes describe trajectories whose directions of convexity lie to the right of the path 

 of the cyclone. 



3. All left-hand floes (to the left of the cyclone path at the initial moment) and some of the 

 right-hand floes (to the right of the path of the cyclone at the initial moment) describe counter- 

 clockwise trajectories; and remaining floes follow clockwise trajectories. The slower the cyclone 

 movement, the greater will be the number of floes which describe counterclockwise trajectories. 

 In the case of a stationary cyclone, all floes will describe counterclockwise trajectories. 



4. Before the center of the cyclone crosses the initial line of the floes, all floes move up- 

 ward (according to the orientation of the figures) and then they begin to move in the opposite direc- 

 tion. In this connection, when the center of the cyclone approaches the initial line of the floes, 

 concentration occurs on the left side of a cyclone path and scattering on the right. After the cyclone 

 center passes over the initial line, the floes begin to move in the opposite direction and after pass- 

 ing through the entire cyclone region they are almost the same distance from the center of the 

 cyclone as at the initial moment. 



5. The displacements of the floes in a direction perpendicular to the path of the cyclone are 

 considerably smaller than their displacements parallel to the path of the cyclone. From figure 138 

 it is evident that the horizontal distances between the left-hand floes gradually increases during the 

 passage of the cyclone and consequently a right-to-left scattering of the ice occurs to the left of the 

 cyclone path. On the other hand, the horizontal distances between the right-hand floes decrease 

 more and more as the cyclone passes over, which inevitably leads to a concentration of the ice and 

 also to hummocking when the ice floes become sufficiently close packed. Here, as can be seen 

 from figure 138, a ridge of hummocks forms in connection with the passage of the cyclone and 

 moves from left to right at a rate equal to the rate of movement of the cyclone. Other conditions 

 being equal, the slower the cyclone moves, the larger this ridge will become. Thus, during the 

 passage of a cyclone the left-hand ice fields break up and their parts scatter, while the right-hand 

 ice fields hummock. 



379 



