Fig. 3. 



In winter (Fig. 4) the inclination of the higher isobars is very strong 

 and increases upwards beyond the 150 mb. level. But the difference 

 beween the southern section and the average conditions in the northern 

 hemisphere is probabty smaller- than in summer. 



Outside the equatorial regions the direction and speed of the wind 

 in the free atmosphere is determined by the equilibrium of the Coriolis 

 force and the pressure force. This fact allows the use of the meridional 

 inclination of the isobaric surfaces to find the component of the wind 

 along the circle of latitude — i.e., the so-called " zonal " component of 

 the general circulation. It must not be overlooked that the zonal wind 

 component as computed from the average distribution of pressure gives 

 a rather imperfect picture of the actual wind conditions since the meri- 

 dional components of the motion are neglected and components towards 



59 



