Time Zones and Daylight Savings

Time zones
Standard time was fixed in 1883. Lines at every 15° longitude were drawn down a map of the Earth to create 24 international time zones differing from each preceding and following zone by one hour.  Because of political boundaries, these lines often zigzag and depart from the 15° rule.

Setting time zones in Windows   On the second tab of the Date/Time control panel is the time zone map. You can set the time zone it is by dragging the "sunny" panel until it is over your time zone. Note that are several zones within each panel, for instance there is a separate zone for both Canada and the US in each of the North American time zones. Use the arrow keys to explore the various zones within a panel.

In Windows95 there are actually 51 separate entries in the list of time zones, even though there are 24 unique panels that circle the earth. These entries have unique rules for time difference from UTC, there are separate entries for India and Australia where the time zones are not whole hour increments from GMT.

Daylight Savings Time
Daylight Saving Time is attained by forwarding the clock one-hour. In 1967 the Uniform Time Act went into effect in the United States. It proclaimed that all states including D.C. were to observe Daylight Saving Time starting at 2 A.M. on the last Sunday in April (moved to the first Sunday in April in 1986) and ending at 2 AM on the last Sunday in October. Any state could exempt itself and Arizona, Hawaii and part of Indiana are exempt.

Forwarding the clock ahead one hour during summer months is common throughout the world. Generally it is done in Western Europe on the last Sunday in March and changes back in the last Sunday in September.  Examine the Time Zone map to explore.

Ireland, Paraguay and the Dominican Republic adjust their clock in their respective winter months instead of summer.