“The only reason for time is so that everything doesn't happen at once.”
By convention, weather scientists use the twenty-four-hour clock, and use one time zone, Greenwich Mean Time (GMT).
Your email box is full of Greenwich Mean Time (GMT) references that you probably didn’t know about! Do your emails contain something like this:
“Tue, 29 Nov 1999 15:20:46 -500 (EST)”
Ever wondered what the “-0500” (or equivalent) means? It is the time offset from GMT. In this example, EST (Eastern Standard Time) is 5 hours behind GMT.
The U.S space shuttle uses Greenwich Mean Time.
Greenwich Mean Time is also known as Universal Time (UTC). To convert to local time, you must know the time difference between GMT and local time for both standard time and summertime (daylight savings time). Not all states (or countries) observe daylight savings time.
The U.S. has 7 times zones: Atlantic, Eastern, Central, Mountain, Pacific, Alaska, and Hawaii.
There is no “official” information on world time zones because nations are sovereign powers that can and do change their timekeeping systems as they see fit.