If you didn't remember that Daylight Savings Time began for most parts of the U.S. you are probably late for an appointment right now. Yep, last night, at 2AM local time, clocks were supposed to jump 1 hour ahead (as I said, in most parts of the U.S.).
One problem with daylight savings time, and this is a real problem for software, is that not everywhere changes to DST on the same day. In fact, the U.S. used to switch to DST much later, and switch back to Standard Time much earlier.
DST's advantages and disadvantages have been debated for a long time, and continue to be debated. Studies of the switch to an earlier DST in the U.S. and Australia have shown negligible impact on energy use.
- In Western Australia during summer 2006–07, DST increased electricity consumption during hotter days and decreased it during cooler days, with consumption rising 0.6% overall.
- Although a 2007 study estimated that introducing DST to Japan would reduce household lighting energy consumption,a 2007 simulation estimated that DST would increase overall energy use in Osaka residences by 0.13%, with a 0.02% decrease due to less lighting more than outweighed by a 0.15% increase due to extra cooling; neither study examined non-residential energy use. DST's effect on lighting energy use is noticeable mainly in residences.
- A 2007 study found that the earlier start to DST that year had little or no effect on electricity consumption in California.
- A 2007 study estimated that winter daylight saving would prevent a 2% increase in average daily electricity consumption in Great Britain.
- A 2008 study examined billing data in Indiana before and after it adopted DST in 2006, and concluded that DST increased residential electricity consumption by 1% to 4%, primarily due to extra afternoon cooling.
- The U.S. Dept. of Energy (DOE) concluded in a 2008 report that the 2007 U.S. extension of DST saved 0.5% of electricity usage during the extended period.
This the great advantage to radio-controlled or somewhat misnamed "atomic" clocks and watches. They sync their time with the 60 Hz radio signal emitted from the transmitter in Ft. Collins, CO. When it finds the signal it decodes the time then sets itself. The Ft. Collins transmitter has a radius of 1864 miles, so most of the United States with the exception of Hawaii and Alaska have access to it.
A real atomic clock uses whose operation is based on an atomic process, typically the frequency of electromagnetic radiation associated with a specified energy-level transition in an element such as cesium.
Since many don't have access to either of these services, if you want to know what time it is, accurately, you can use one of many web sites that track official time.
Examples are:
The NIST Web Clock (US Time)
Gchart (worldwide)
And if you're already late today ... good luck!
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