Day-Light Saving Time (DST)

Introduction

Daylight-saving time is a system established to reduce electricity usage by extending daylight hours (clocks are set ahead one hour). Why is this done? Because at different times of the year – in the spring/summer -- , there is more light than darkness, and some of this light is early in the morning when people are sleeping and is wasted. So for example, if the sun rises at 50.0 am during standard time in June and sets at 7.00 pm, daylight savings transfers the “hour of light” one hour before, so the daylight is now from 6am – 8pm. This is important as a lot less energy is needed during daylight hours than during evening hours. It also gives us the benefit of an hour extra sunlight to enjoy the outdoors in the summer.

This year, standard time begins on at 2.00 am on on Sunday, November 2, 2008 and daylight-saving time begins Sunday, March 9, 2009. In the past, daylight-saving time began in April and ended in October. However, an energy bill signed by President George W. Bush on August 8, 2005 extended daylight-saving time as part of a long-term solution to the nation's energy problems. The new law extended daylight-saving time by four weeks - beginning three weeks earlier and ending one week later. Also under this law, the entire state of Indiana now observes daylight-saving time. Prior to the new laws, only certain areas of the state observed the time changes.
There are a few exceptions to the above. In the United States, Hawaii and most of Arizona do not follow daylight-saving time – which is why the clocks at both ends of Hoover Dam (One side Nevada and the other side Arizona – are the same at one part of the year and an hour different during the other part of the year.

About Other Countries:
--About 70 countries around the world observe daylight-saving time.
--Neither China nor Japan observes daylight-saving time.
--Many other countries refer to "daylight-saving time" as "summertime."

Its main purpose is to increase the daylight time or summer time (as it is called at many places) or to make use of more daylight in those areas where the difference between daylight time and the nighttime is more. If you are living near the Equator, the day and night times are almost equal - 12 hours each; but as you go towards North Pole or South Pole regions the day time, especially the morning time, is more in Summer. Near the North and the South Pole both day and night are of six months duration. People go to Norway to see Midnight Sun in Summer. It gives more daylight time in the evenings in comparison to morning.

In this process the clocks are set one hour backward to increase the daylight time, from morning to evening, in summer (in March/April); then again are set one hour forward (or say are revert back to the original time) in winter (in October/November). See the dates to set these times in the US and in EU here.

The US has been observing this DST device since 1966 from at 2.00 am on the first Sunday of April to 2.00 am the last Sunday of October (for almost 7 months). But from this 2007, most of the US cities will begin DST from 2.00 am of the 2nd Sunday of March and 2.00 am of the 1st Sunday of November.

In the US, all states change their time at different times - at their own local time. It should be noted that the US and Canada have eight different time zones.

In Europe
Europe also observes the DST device to save daylight in summer. In the European Union, Summer Time begins and ends at 1.00 am Universal Time (UT) or Greenwich Mean Time (GMT). It begins on the last Sunday of March and ends on the last Sunday of October. In EU all states change their time at the same time - since their time changes at standard time (GMT).

How the Time Changes
In fact this changing time process doesn't save the daylight time, it just increases one hour daylight time, from the morning till evening, for the use of the people. It gives more daylight in the evening, and for the same reason it saves energy also.

In the US, The clock is set at 2.00 am at local time. In Spring (Spring starts from March 23), the clock (not the time) is set one hour forward, from 1.59 am to 3.00 am; and in Fall (Fall starts from 22 October) it is reset to one hour backward from 1.59 am to 1.00 am.

While in the EU, the clock changes at 1.00 am UT or GMT. In Spring it changes one hour forward from 12.59 to 2.00 am; while in Autumn it goes back from 1.59 am to 1.00 am.

Why should it start at 2 am? The website LiveScience explains that's it's pretty much the least disruptive time of day to make a switch. After all, most of us are asleep. Those who work on Sunday usually start later than 2 am. That is why this time has been chosen just for convenience, minimal disturbance and practicality. Some areas of the US do not observe DST - Hawaii, American Samoa, Guam, Puerto Rico, the Virgin Islands and Arizona.