->  DW> the Northern Hemisphere. This makes sense, since the Equation of Time 
->  DW> has a far greater effect in the northern winter than the southern one. 
 
-> That's when we are at perihelion. 
  
That is one of the two factors that are involved. The other is the tilt 
of the Earth's axis. The two factors almost cancel each other out 
during the northern summer / southern winter, so at that time of year 
sundials show pretty accurate time and sunrise and sunset occur 
reasonably symmetrically about (clock) noon. But during northern winter 
/ southern summer, the two factors reinforce each other, with the 
result, for example, that sundials are about 15 minutes "fast" compared 
with clocks at about the beginning of November, and about 15 minutes 
"slow" in mid-February. Sunrise and sunset are similarly affected. 
  
I have a computer program that calculates this. I'll post it when I 
have a chance. 
  
                          dow 
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