1915- î*^o- 5- ROALD Amundsen's antarctic expedition: meteorology. 53 



and velocity of the wind. The same was done at Framheim. From the 

 direction we can find the direction of the gradients and from the velocit}- 

 the magnitude of the gradients in both places. The directions locate the 

 minimum or maximum of pressure, and the magnitudes give the distribution 

 of pressure at the level of the stations. We have thus the necessary means 

 for constructing a chart with isobars at the lower level, and can take out 

 the pressure at that level in the vertical of the station of which the height 

 is to be computed. 



The formulae I have taken to compute the directions and magnitudes 

 of the gradients are, 

 when G is the magnitude of the gradient in mm. per degree of meridian, 



a = i-^OOQ . = 0.0001224.. 



o = the mass of a cubic metre of air, 



the weight of i cub. m. of air 



the normal gravity 



1.293 273 b ^ b 



= ^^ • ^^- ■ = 0.04736 , — 



9.806 273 -f/ 760 ^'^ 273+/' 



where b = the pressure in mm. 



t = the temperature of the air, C. 



(1 = the angle of the wind's deviation from the gradient, 



2 rr 

 v)=^- — — =0.00007292 the angular velocity of the 

 86364 



rotation of the Earth, 

 f = the velocity of the wind in metres per second, 

 (f = the latitude, 

 k = the coefficient of friction, 



we have 



— G sin a = 2ijv sm rr 



o ' 



^- G cos a = k. V 



2 10 sm œ 



tan ft = 7 — ^ 



k 



^ 2 w sm (f. o R q 



sin a. u cosç u 



Putting k = 0.00008 (inland) and / ^ — 17°, we have 

 latitude 78'' 79O 80« 



a = 60O 45' 6o'J 48' 6o'5 53' 



Q 



— =0.18 for latitudes 78^ — 80^' and 740—710 mm. 



t; 



