[LEAPSECS] time zones and DST

[Rob Seaman]

Tony Finch wrote:


> This is why DST is a sensible solution to the problem of the  

> mismatch between natural human preferences and inflexible timetables  

> based on mean solar time.


I don't think "inflexible" is the right choice of words, but I'll let  
it pass to make a more basic point.  DST only offers the opportunity  
for sensible seasonal solutions.  In the absence of coherent  
government oversight (an oxymoron if ever there was), no such solution  
will be sensible.

I continue to question whether DST is the right platform for  
accommodating secular shifts in the underlying worldwide civil  
timescale.  Some sort of longitudinal study would be required to build  
a case for any "solution" that doesn't stabilize the timescale.


> Your phrasing there makes it sound like you think DST increases the  

> supply of daylight.


No, just that the pressure to do the job right is greater when the  
resource is in shorter supply.  Since DST is actually applied  
precisely when it spills over both further into the morning and  
further into the evening hours, I question whether your explanation is  
complete or consistent.


> Having said that, there is a general tendency for time zones to move  

> so that they are centred further west than their nominal meridian.


As with other clock and calendrical issues, there is rather a tendency  
to overgeneralize.  For instance, it would be very interesting to  
contrast DST policies in the southern hemisphere with those in the  
north.  The Earth is very asymmetric north and south and such a study  
would be likely to reveal interesting usage patterns relating to  
underlying human factors.

Rob