When you cross the line between two time zones you usually re-set your watch forward or back one hour from its current setting. Set your watch back if you are traveling west, and set it ahead if traveling east. If you are on a flight that will bring you across several time zones, probably the better idea is to set your watch for the current time at your destination and get some rest. Also, get up frequently to stretch and exercise your legs-- don't neglect this. In addition, if you cross the International Date Line, change to the next day if going west, and go to the day before if going east. There are some places on earth where times differ between zones by 30 minutes and not by an hour. There are also places where the time zones do not geographically follow the theoretical or originally defined time zones.
360° of longitude divided by 24 time zones gives 15° per time zone (average)
There are 24 time zones. Divide 360 degrees longitude by 24 and you get 15 degrees for each one-hour time zone.
Answers.com "operates" across all time zones.
To make it easer for people to tell time across the world
China
move it back one hour.
Geographically, South Africa lies across two time zones, but the country runs on a standard time zone called SAST or South African Standard Time which is based on the exact time zone in Pietermaritzburg and corresponds to GMT+2.
If you get an atomic clock it can be set to adjust for the time zone, and as a bonus will always show the correct time.
The Central Time Zone is east of the Mountain Time Zone.
8.00 hour
8.00 hour
The Pacific Time Zone is west of the Mountain Time Zone.