Also, known as the Local Mean Time (LMT), it is a kind of solar time. In other words, it is one of the methods of calculating and keeping the duration of time by observing the sun’s location in the sky.
It differs from the horário padrão insofar as a country’s law determines the latter keeping in mind the distance of the central meridian of that country from the Prime Meridian (0° Longitude).
In contrast, Local Mean Time is region-specific and depends on the sun’s position over the meridian running through that region.
Until the late nineteenth century, local mean time used to determine the clocks of a region. The tool that was used to determine the local mean time of a place was called sundial.
However, with the railways becoming a predominant means of transport during the late nineteenth century, a uniformity of time became the need of the hour. It was because the railways’ administrators could not prepare a uniform train time-schedule with different stations following different time clocks. Faced with this dilemma, the officials decided to introduce the concept of a standard time.
How does Local Time work?
It is a well-known fact that the earth rotates from west to east upon its axis. Consequently, the sun seems to set in the west and rise in the east.
However, not all parts of the earth experience daylight at the same time. It takes 24 hours for the earth to complete a rotation of 360 degrees. In other words, the earth traverses 15 degrees in one hour or one degree in four minutes.
Consequently, the earth has been divided into 24 time zones with each of them being 15 degrees apart from each other.
The rate of time at which the sun moves over a specific degree of longitudes sets a region’s horário local with relation to the Prime Meridian.
For example, the local time of Bhutan (Thimpu) which is located at 90° longitude to the east of the Prime Meridian will be 6 pm if it is noon at the Greenwich Meridian (0°) as the time difference between them is of 6 hours.
Similarly, there will be considerable differences between the local time of New Delhi located at 77.21° E and the local time of Silchar located at 92.78° E.
Advantages of Local Time
Even though in contemporary times, the usage of local time has become almost obsolete, it does have some indirect advantages.
- Synchronisation with the earth’s rotation: It allows us to synchronise our clock with the earth’s rotation.
- UT 1: The UT1, a version of the Universal Time, which is used as one of the reference points for the determination of the standard time of all other countries, is the local time of the Greenwich Meridian.
- Provides the precise time for time-bound activities: It gives us an idea of the exact time for a particular location which is essential to schedule specific time-bound activities like transportation.
- Astronomers’ friend: Astronomers all over the world depend on the local mean time (LMT) to enunciate their observations.
- Dictates people’s daily activities: Despite the standard time determining a country’s time clock, it is the local time that regulates people’s day to day activities.
Disadvantages of Local Time
The concept of Local Mean Time was not given up for no reason during the late nineteenth century. The following are some significant drawbacks of the local time:
- Prevents administrative uniformity: It acts as a significant obstacle in the path of establishing administrative uniformity.
- Generates a lack of coordination: It creates a lack of coordination as far as the economic exchange between different cities, villages and regions are concerned.
- Generates chaos: It creates too much confusion from the administrative point of view.
- Temporal differentiation and its impact on the cognition of the residents: It creates a sense of difference among the people living in different time zones.
- Obstructs national integration: Too many time zones act as a blockade in the path of national integration.