Re: Why daylight time chgs are not the same rate sunset/sunrise?

Area: Earth Sciences
Subject: Why daylight time chgs are not the same rate sunset/sunrise?
Message ID Number: 885511711.Es

Hal:

This question of yours has made for an interesting bit of research for me 
as well as providing a good lesson in how NOT to approach answering a 
question of this type.

I knew of nothing like you described from anything I had read or 
experienced in the past concerning seasonal variations in the length of the 
day.  So, I started off by trying to locate anything that I could lay my 
hands on.  I found no evidence whatsoever of a mechanism for what you are 
describing.  Next, I tried to enlist the help of an astronomer acquaintance 
of mine.  However he was too busy to really be of any help.  So I next went 
back to the books and studied up as best I could, hoping that I might be 
able to divine the answer myself.  When no indication of a solution was 
apparent I finally did what I should have done first.  

I went to the library and examined old newspapers from January and February 
of this year.  Since I don't have access to a Denver paper, I looked at 
newspapers for New York City and Washington D.C. which are located above 
and below the latitude of Denver.  What I found was absolutely no evidence 
of the phenomenon you describe.  Therefore unless you can provide me with 
evidence to the contrary I maintain that your source is wrong!  Perhaps the 
newspaper's college intern was having a bad day when he ran the numbers.

I found that on average, the length of day increased by about two minutes 
or so per day -- about a minute in the morning and a minute in the evening. 
I also went to a table of day length data based on latitude and found 
nothing to suggest that your latitude experiences anything out of the 
ordinary. There is, of course, the minute possibility that you are living 
under the influence of an as yet undiscovered nannometer-sized blackhole 
and that it is creating some kind of periodic distortion in the space-time 
continuum; however parsimony suggests otherwise.

But seriously now, if you can document this for me I will investigate 
further, otherwise I think I'll leave it up to the Bermuda triangle folks.

Dr. Clay Harris
Dept. of Geography/Geology
Middle TN State University
cdharris@frank.mtsu.edu