Time Zones - USA and India

The different times of USA and India set me to find out about the time zones of the world. So let me share a bit of my knowledge.

UTC is the Co-ordinated Universal Time used as a benchmark. I would skip some of the history behind time which is easily available in various learning websites. UTC is a primary standard time by which the world regulates clocks. The term GMT Greenwich Mean Time already has a successor in UTC and no longer has a precise definition.

USA uses 9 standard time zones .From east to west they are Atlantic Standard Time (AST), Eastern Standard Time (EST), Central Standard Time (CST), Mountain Standard Time (MST), Pacific Standard Time (PST), Alaskan Standard Time (AKST), Hawaii-Aleutian Standard Time (HST), Samoa standard time (UTC-11) and Chamorro Standard Time (UTC+10).

Each zone has a daylight saving time …so what is daylight saving? Daylight saving has been a subject of debate for a long time. However DST is a change from the standard time to utilize the daylight better by having the sun rise 1 hour later in the morning and set 1 hour later in the evening …It begins at 2:00 a.m. on the second Sunday in March. On the first Sunday in November areas on Daylight Saving Time return to Standard Time at 2:00 a.m.

The names in each time zone change along with Daylight Saving Time. Eastern Standard Time (EST) becomes Eastern Daylight Time (EDT), and so forth. Arizona, Puerto Rico, Hawaii, U.S. Virgin Islands and American Samoa do not observe Daylight Saving Time.

Florida lies in the Eastern time zone with a standard time of UTC-5hrs and daylight time of UTC-4hrs.

India follows an Indian standard time (IST) which is UTC+5:30 and does not observe DST. IST is calculated on the basis of 82.5 deg longitude in Shankargarh Fort, Allahabad, Uttar Pradesh

DST was briefly used during the Sino-Indian and the Indo-Pak wars. Though after independence IST was officially adopted, Kolkata and Mumbai had their own times till 1948 and 1955 respectively.

India’s East-West distance covers over 28 deg of longitude resulting in the sun rising and setting almost 2 hrs earlier in the eastern border.
The Indian government is not ready to split the nation into multiple time zones though there is pressure from the Northeastern states of the country. Since the Plantations Labour act 1951 allows Central and state governments to set a local time in an industrial estate, Assam tea gardens follow a separate time zone known as – Tea garden time or Bagantime which is 1 hr ahead of IST.