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Revision as of 07:45, 18 September 2002 by Khendon (talk | contribs) (s/pedants//)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)Daylight saving time (also called "DST", or "Summer Time") is the local time a country adopts for a portion of the year, usually an hour forward from its standard official time.
It is a system intended to "save" daylight (as opposed to wasting it by sleeping, say, while the sun shines). The official time is adjusted forward during the spring and summer months, so that the active hours of work and school will better match the hours of daylight.
DST is not universally accepted; many localities do not observe it. Nevertheless, proponents claim that DST helps more than it hurts. The primary claim is that it reduces energy consumption. Opponents claim that there's not enough benefit to justify needing to adjust clocks twice per year.
DST is particularly unpopular among people working in agriculture because the animals do not observe it, and thus the people are left out of synchronization with the rest of the community.
For fairly obvious reasons, DST is a temperate zone practice: day lengths in the tropics do not vary enough to justify DST.
The amount of the time shift varies, but one hour is the most common. The dates of the beginning and ending of DST also vary, but it commonly begins in the Northern Hemisphere at 2:00 AM on either the first Sunday in April or the last Sunday in March, and ends at 2:00 AM on the last Sunday in October. In the Southern Hemisphere, the beginning and ending dates are switched.
The mnemonic "Spring forward, Fall back", tells how to reset clocks when the time switches.
The expression "Daylight savings time" (with the extra s) is a common alternate form, considered a usage error by many.
External Links
- Straightforward, good-looking discussion of DST, suitable for anybody of about age ten or over
- DST changeover times throughout the world
- World Time Server
- Time Zone Converter
Links about changing or abolishing DST: