Standard Meridian of India – To establish a local mean time standard, a particular geographical area uses a single standard time instead of solar time and a meridian (longitude) determined by local circumstances. Every country establishes a standard meridian, which is the central longitude of the entire country at the same time being the same everywhere.
The five states through which the Indian Standard Meridian passes. The standard meridian of India passes through the following states –
- Uttar Pradesh
- Madhya Pradesh
- Andhra Pradesh
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Standard Meridian of India
The Standard Meridian of India having the longitude 82°30’E, which passes through Mirzapur in Uttar Pradesh is considered as the standard time for the whole country.
How was the Standard Time of India decided?
Local time differs from one place to another. Dwarka in Gujarat and Dibrugarh in Assam are about an hour and 45 minutes apart in local time in India. Hence, the standard time of a country must be based on the local time of its central meridian. The longitude of 82½° E (82° 30’E) is considered as the standard meridian. In this meridian, the time stated or mentioned is considered to be the standard time for the entire country. This is known as Indian Standard Time (IST).
- India lies in the northern hemisphere.
- The Tropic of Cancer crosses the country almost halfway (23°30’N).
- The main land of India extends between latitudes 8°4’N and 37°6’N.
- India stretches between 68°7’E and 97°25’E longitudes from west to east.
- Each degree of longitude means a change in time of four minutes.
- During the summer months, the sun rises about two hours earlier in the east (Arunachal Pradesh) than in the west (Gujarat).
- In Indian Standard Time, the time at 82°30’E longitude has been taken as the local time.
- Longitudes along this meridian are also known as the Standard Meridian of India.
- There is a two-hour time difference between Gujarat and Arunachal Pradesh.
- As a result, the time along the Standard Meridian of India (82°30’E), passing through Mirzapur (in Uttar Pradesh), is taken as the standard time in India.