If lines of longitude have anything to do with measuring time how does that relate to the number of time zones in China?

Answer 1

It actually doesn't relate at all. By order of the central government of PRC, the

entire nation, even out to Mongolia, keeps Beijing time. The results are that in

Mongolia, the sun can rise around 11:00 in the morning and set around 11:00

at night, and in vast swaths of western China, nobody much knows or cares

what Beijing wants or what's going on way over there. I have the honor to be

able to report both of these local phenomena from personal experience, boots

on the ground, etc.

Answer 2

Longitude lines divide the spherical surface of the Earth into 360° "horizontally", based on a central meridian at Greenwich and 180° to either east and west. The Earth has a day divided into 24 hours, and the solar time at any given location will be one hour later in the day than a location 15° to its west (360/24 = 15).

So time zones are nominally set up with a width of 15°. When it is noon at Greenwich, it is 1 PM along the meridian of 15°E and 2 PM at the meridian of 30°E, and so forth. A time zone is centered on each meridian with a spacing of 15°. For example, New Orleans, LA, on the 90° west meridian, is in the geographic center of the US Central Time Zone (Greenwich time minus 6 hours).

When a time passes midnight to the east of a location, the new day begins. Officially a day begins at just past midnight at the International Date Line.

Adjustments to the Time Zone Boundaries

Time Zones have been adjusted from the ideal 15° to accommodate political and commercial boundaries. For example, the US Eastern Time Zone is nominally 5 hours earlier than Greenwich, centered on 75° W. But in Canada, it includes areas as far west as the center of the US Central Time Zone (90°).

The state of Indiana is now entirely on Eastern Time, although it falls mainly with the Central Time Zone as well (this was part of the famous debates over Daylight Savings Time, at the related link).

Answer 3

The sun moves around the earth's 360 degrees of longitude in 24 hours ... that's 15 degrees per hour.

Each 15 degrees change of longitude should correspond to 1 hour of the sun's motion across the sky.

The boundaries of the official time-zones have been zig-zagged in many places in order to avoid cutting

across a city. In the US, they're adjusted in many places to follow state lines.

But in terms of the sun's motion, 15 degrees is still 1 hour. You can see this during a long trip by air.

Move your watch 1 hour every time your position changes 15 degrees in longitude, and your watch will

always be right in step with the sun's position in the sky.

If you're traveling a route that takes you far north or south ... where the longitudes crowd together ...

you cover longitudes so fast that your trip can actually keep pace with the sun, or even outrun it.

I don't know the official time set-up in China. On a couple of occasions when I was there, I was told

that the whole country keeps Beijing time. I don't know whetheer that's true, but if it is, then that would

explain some of the peculiar sunrise and sunset times I experienced. In Ulaan Batar, Mongolia, in particular,

I distinctly remember that the sun rose routinely around 3 AM, and set routinely around 4 PM. This wasn't any

Arctic polar effect, as my latitude there was about the same as common latitudes in North Dakota and Montana.

It was certainly the effect of setting the nation's clocks to the time that was a lot more appropriate several zones

further east.

Answer 4

The Prime meridian determines time. The International Date Line determines days because it is a separator of Day 1 and Day 2. The equator, Tropic of Cancer, Tropic of Capricorn, Arctic Circle...etc..

Answer 5

China only has one time zone, despite its vast east-west expanse. The entire country follows Beijing Time (GMT+8). This decision was made for political and administrative reasons, to promote unity and simplify logistics. So, even though China covers several geographical time zones, it operates under a single time zone.