Monday, November 8, 2010
In Defense of Daylight Savings Time
Last week I railed against changing the clocks, and most of my blog followers agreed with me. I invited dissenting opinions to share their point of view, and today I’d like to present a guest blog by my brother-in-law, Larry O’Donnell. (You’ve met Larry before!)
Changes in Latitude, Changes in Attitude by Larry O’Donnell
Why do we need those pesky time zones and seasonal time changes?
Some of the reasons are socio-economic, some are to avoid chaos and some actually save lives.
The Sun gives us a means of telling time by appearing to move from east to west. The sun dial was developed (and used for centuries) as way of determining time. There were an infinite number of time zones because the sun dial was accurate only where it stood. That didn’t matter since there was little commerce and almost all of it was local. Once land and sea transportation and commerce went to steam, the need for coordinated time became obvious. Ultimately, a general agreement led to time zones. This convention simplified navigation, which used time and the angular altitude of stars to determine position.
In theory, each of the 24 time zones is 15 degrees of Longitude wide. The middle of the zone is where noon occurs with the Sun directly overhead, at the Equator on the solstice.
In practice, the time zones gerrymander according to national, State, and county borders. Sometimes they are drawn to topographic features, mostly rivers. Florida has two time zones divided by the Apalachicola River.
In order to position daylight during the most productive times of the day an adjustment is made by advancing or retarding the clock. Navigation ignores this change by using UTC or what used to be Greenwich Mean Time (GMT) to measure against star sightings. There has been considerable debate about the use of DST, and States are permitted to legislate their participation. Arizona and Hawaii, for instance, do not change to DST.
There are those who claim there is an energy saving benefit. There those who refute that claim. Some folks believe it improves the quality of life by permitting working people daylight in the evenings for recreation or chores. One thing that is relatively certain, where it has been studied, is that there are fewer pedestrian deaths and injuries during DST. Studies clearly indicated the number of pedestrian casualties in the same locations were significantly higher starting immediately after the conclusion of DST.
The two time zone idea would be okay for the people living in the middle of the zone. But the people living on the edge of their zone would have some difficulties. Imagine if it were 6am in both New York City and Wichita, Kansas. In New York, it would be dawn, but the sun might still be an hour and a half away from Wichita.
I like the extra hour of sleep in the fall and despise losing it in the spring but other than that, I think the system provides better quality of life, in the summer.