564 



H. MOHN. METEOROLOGY. 



[norw. POL. EXP. 



depth. The first condition is not fulfilled in the case of the polar ice, as we 

 see from the Table, p. 562, the mean annual temperature, M, being higher 

 than that of the surface, and increasing with depth. Nor does the second 

 condition agi'ee with our facts, as will be seen further on. 



The Table on p. 562 shows that the phase-angle decreases with depth. 

 This signifies that the greater the depth, the later do the annual minima and 

 maxima of the temperature occur. This lag or retardation of the heat-wave 

 is proportional to the depth. I have computed the most probable value of 

 the coefficient of this retardation from the given values by the method of 

 least squares. 



or retardation r = 14'°65 per metre. 



• The computation with the 7 values from h = to 7^ = 3 m. gives 

 ^ = 262-° 61— 16-° 30. h and M.E. = + 0-°9. As the first and last values, for 

 and 3 metres, are extrapolated, the first found equation for A is to be 

 preferred. 



The retardation r of 14-° 65 per metre corresponds to 14-86 days per 



metre, and is equal to 0-2557 radian (»"7qk 



The Table on p. 562 gives as the annual ranges of the temperature at 

 different depths, 



