Lecture – 03 World Time Zones

 

World Time Zones

Greenwich Mean Time (GMT):

v  It is the name for the mean solar time of the longitude (0°) of the Royal Greenwich Observatory in

England. The meridian at this longitude is called the Prime Meridian or Greenwich Meridian.

v  Rotation of Earth of 360° in one day or 24 hours. Therefore, 15° in one hour or 1° in 4 minutes.

v  Earth rotates from West to East, so every 15° we go eastward, local time is advanced by 1 hour.

v  If we go westward, local time is retarded by one hour. 

Ø  East of Greenwich → see the sun earlier → Gain time (East-Gain-Add). 

Ø  West of Greenwich → see sun later → Lose time (West-Lose-Substract).

v  India is 5 hrs 30 min ahead of GMT. 

v  From Greenwich to 180° E → Gain 12 hours. Similarly, from Greenwich to 180° W → Lose 12 hours.

v  Thus, a difference of 24 hours between the two sides of the 180° meridian. This is the International Date Line (IDL).

v  Thus, if a traveler is crossing IDL: East to West → Loses a day; West to East →gains a day

v  IDL passes through the middle of the Pacific Ocean.

v  Local time varies from one longitude to another longitude. 

v  In the world, there are 24 time zones. 

v  USSR- 11 Time zone

v  USA- 4 Time zones (Pacific Time, Mountain Time, Central Time, Eastern Time)

Standard Time and Time Zones:

v  If each town were to keep the time of its own meridian, there would be much difference in local time between one town and the other.

v  Travelers going from one end of the country to the other would have to keep changing their watches if they wanted to keep their appointments. This is impractical and very inconvenient.

v  Most countries adopt their standard time from the central meridian of their countries.In larger countries such as Canada, U.S.A., China, and U.S.S.R, it would be inconvenient to have single 

v  time zone. So, these countries have multiple time zones.

v  Both Canada and the U.S.A. have five time zones —the Atlantic, Eastern, Central, Mountain, and Pacific Time Zones.  

v  The difference between the local time of the Atlantic and Pacific coasts is nearly five hours. U.S.S.R had eleven time zones before its disintegration.

International Date Line: 

v  International Date Line is an imaginary line where the date changes by exactly one day when it is crossed.

v  The International Date Line in the mid-Pacific curves from the normal 180° meridian at the Bering Strait, Fiji, Tonga, and other islands to prevent confusion of day and date in some of the island groups that are cut through by the meridian. 

Why International Date Line is Zig Zag?

v  Some groups of Islands (Polynesia, Melanesia, Micronesia) fall on either side of the dateline. 

v  If the dateline was straight, then two regions of the same Island Country or Island group would fall under different date zones.

v  Thus, to avoid any confusion of date, this line is drawn through where the sea lies and not land. Hence, the International Date Line is drawn in a zig-zag manner. 

Indian Standard Time: 

v  The local time of places which are on different meridians is bound to differ.

v  In India, for instance, there will be a difference of about 1 hour and 45 minutes in the local times of Dwarka in Gujarat and Dibrugarh in Assam.

v  In India, the longitude of 82 1⁄2° East (82° 30’East)  is treated as the standard meridian. The local time at this meridian is taken as the standard time for the whole country. It is known as the Indian Standard Time (IST).

v  States through which IST passes are UttarPradesh, Madhya Pradesh, Chhattisgarh, Odisha, and Andhra Pradesh.

Issues With Indian Standard Time: 

v  Vast latitudinal extent: Indian mainland extends between latitudes 8°4’North and 37°6’North and longitudes 68°7’East and 97°25’East.  

Ø  There are nearly two hours difference between the easternmost and westernmost parts of the country.

Ø  This can also result in some confusion and inconvenience for people traveling across different regions.

v  Disruption in circadian rhythm: The North-eastern States witness early sunrise at around 4:30 am and late sunset due to a single time zone. It badly affects the lives of local people and disbalances the biological clock.

v  It also increases the alienation of local people of the North-eastern States from the mainland due to the wide gap in time.  

Need of Two Time Zones: 

v  It may increase energy efficiency by utilizing daylight time optimally. India can save up to 2.7 billion units of electricity every year.   

v  During the colonial period, there were references of separate time zones like- ChaiBagaan time, Bombay time, Calcutta time, etc., without any inconvenience.  

v  It will align time with the biological clock of people; this will improve the health of people and increase productivity & efficiency and will provide a boost to the economy.  

v  It will reduce the alienation of local people by addressing their needs and issues like road accidents, women’s safety, etc.  

Daylight Saving Time:   

v  It is the practice of setting the clock forward or backward by generally one hour during the summer months of the year to extend the amount of daylight in the evenings. 

v  The idea behind DST is to take advantage of the longer days of summer to save energy, reduce traffic accidents, and provide more recreational opportunities in the evenings.

v  It is observed in many countries around the world.

v  Over 150 years ago, the British introduced the Chai-bagan time (CTZ). For Assam's tea estates, collieries, and oil industries, it was set one hour earlier than Indian Standard Time (IST).

Arguments for Shifting Time Zones: 

v  According to the research of the National Institute of Advanced Studies, Bangalore, if we shift or change the IST, it can save around 2.7 billion units of electricity. 

v  The report of the Planning Commission, in 2006, also supported the idea of adopting different time zones.

v  The Council of Scientific & Industrial Research’s National Physical Laboratory (CSIR-NPL), in its report (in 2018), also presented the necessity of two time zones.

Challenges with Two Time Zones: 

v  There may be confusion and lack of coordination in government work. 

v  Implementation of two time zones requires proper synchronization of railway traffic, which is a complex and time taking process. 

v  The level of illiteracy is very high in India so there can be chaos among people of border zones of two time zones in understanding the mechanism.

v  There is a lack of infrastructure and capacity in the existing laboratories to maintain two time zones.  

v  The dividing line in the form of two time zones in the country can create several political consequences like separatism, regionalism, etc.  

 

 MCQ 

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