Because meridians are straight lines and these do not always match political and social boundaries. If we followed the meridians exactly they would arbitrarily divide communities. So the Time Zones are adjusted to meet people’s needs.
Why do time zones not exactly follow meridians?
A time zone is an area that observes a uniform standard time for legal, commercial and social purposes. Time zones tend to follow the boundaries between countries and their subdivisions instead of strictly following longitude, because it is convenient for areas in frequent communication to keep the same time.
Why do time zones not always exactly follow lines of longitude?
As Earth rotates on its axis, it moves about 15 degrees every 60 minutes. After 24 hours, it has completed a full rotation of 360 degrees. The scientists used this information to divide the planet into 24 sections or time zones. Each time zone is 15 degrees of longitude wide.
Why timezone line is not straight?
The Earth takes 24 hours to rotate through 360 degree (longitude). Hence, two places that are 15 degree of longitude apart have a difference of one hour. As the Sun rises in the east and sets in the west. This adds up to a difference of 24 hours or one day between east and west of 180 degree line of longitude.
Do time zones always follow the lines of longitude?
For example, in crossing the border from China to Afghanistan there is a three and a half hour time gain! In fact, because time zones do not follow neatly along lines of longitude, there are many places where three or more time zones meet.
How does longitude affect time zones?
1 Answer. so every 15 degrees of longitude equals one time zone.
Why does USA have different time zones?
Why Do We Have Time Zones? The expansion of transport and communication during the 19th century created a need for a unified time-keeping system, and time zones were introduced. The expansion of transport and communication during the 19th century created a need for a unified time-keeping system.
Are time zones based on latitude or longitude?
longitude
They are based on longitude and defined by Earth’s rotation, which completes a full circle (360 degrees) each day (24 hours). Each hour then, Earth rotates through 360/24 = 15° of longitude: the width of one time zone.
Why do we have the concept of time zone class 6?
So if we have the same time, then 12 noon will mean midday at one place, and midnight at another. To avoid such an awkward system, we have the system of time zones, so that everywhere a particular time means the same stage of the day.
Why is the International Date Line zig-zag?
The time difference on either side of this line is 24 hours. So, the date changes as soon as one crosses this line. To avoid any confusion of date, this line is drawn through where the sea lies and not land. Hence, the IDL is drawn in a zig-zag manner.
Why is the Prime Meridian not straight?
But because the Earth is not perfectly round and local gravitational forces vary with terrain, the surface of the mercury at Greenwich was not precisely horizontal relative to the centre of the Earth’s mass. As a result, the vertical line to the stars and therefore the meridian line on the ground were slightly skewed.
Why is IDL not a straight line like the 180 degree meridian?
The international date is not a straight line as to avoid crossing any land mass, which create different dates and timing .
Why each time zone contains 15 of longitude?
One whole circle is made up of 360 degrees. It takes the Earth 24 hours to turn in a circle. So when we divide 360 degrees by 24 hours, we see that the Earth rotates about 15 degrees each hour. 4 Each time zone is set up having 15 degrees of longitude.
What is the relationship between longitude and time?
It takes 4 minutes to travel from one longitude to another. So, generally 1 degree difference in Longitude, causes a difference of 4 minutes. The places located in the East of the Prime Meridian are ahead in time to the places located in the Western Hemisphere.
How many meridians are in a time zone?
24 standard
The system consisted of 24 standard meridians of longitude 15 degrees apart from each other, beginning with the Prime Meridian through Greenwich, England. Each meridian is the center of each standard time zone.
How many meridians does a time zone span?
Each time zone spans 15 degrees of longitude. The “zero” zone is centered on the Prime Meridian which passes through Greenwich, England; it extends east to 7.5°E and west to 7.5°W. The zones are numbered negatively to the west and positively to the east of Greenwich. Some time zones are named as well as numbered.
What country starts the day first?
Oceania is the first place to celebrate the New Year. The small Pacific island nations of Tonga, Samoa and Kiribati are the first countries to welcome New Year, where January 1 begins at 10 am GMT or 3:30 pm IST on December 31.
Is it ever the same day everywhere in the world?
Hi! It’s a matter of time. There is a time in the world that every nation has the same day or date it will a matter of seconds that it will fall on the same exact day of Sunday whether day or night or afternoon or dawn or early morning as long as it is the same day.
Why does China have one timezone?
But in 1949, as the Communist Party consolidated control of the country, Chairman Mao Zedong decreed that all of China would henceforth be on Beijing time for the purposes of national unity.
What are timezones based on?
The Earth is loosely divided into 24 regions (time zones) separated by longitude. Not counting local variations, each line of longitude is divided by fifteen degrees; as a general rule and depending upon which way one travels, time moves forward or backward one hour for every fifteen degrees of longitude.
How time zones are determined?
The idea behind multiple time zones is to divide the world into 24 15-degree slices and set the clocks accordingly in each zone. All of the people in a given zone set their clocks the same way, and each zone is one hour different from the next.