Taking as reference the Meridian 0º of Greenwinch or UTC 0º = 0 hours, the earth is divided into 2 hemispheres, with 12 time zones to the east (0 to +12) and 12 time zones to the west (0 to -12).
There are also countries or localities whose geographical location and/or for convenience, use different intermediate times* bands to the exact meridians 15º as they are: Iran - St. John's - Afghanistan - India (Sri Lanka) - Nepal - Myanmar - Eucla - Northern Territory of Australia - South Australia - Lord Howe Island (in winter) - Chatham Islands. These countries use time slots of 30 or 45 minutes. Most of these time zones are between Asia and Oceania
4 colors to differentiate the time zones - - - that conform to the time bands of 1 hour = meridians of 15º.
In turn, these colors can be practical to visualize the time difference between countries with the same color, since they are multiples of 4 hours. (4 colors).
Eg. If we wanted to see at a glance the time difference between California and the United Kingdom (both countries with the same pink time zone color), the time difference between both countries will be 8 hours, (multiple of 4 hours) (except when one of these countries, this one using daylight saving time and the other one not).
More eg: between New York and Saudi Arabia, both countries in yellow, (except during New York's summer time), the difference between those countries will be 8 hours, or if it were in green, Colorado and France, all them (multiples of 4 h). In the same way it would be with the rest of countries and colors.
|New York /||Saudi Arabia|
|UTC -5:00 / -4:00||UTC +3:00|
|Illinois /||Syria /|
|UTC -6:00 / -5:00||UTC +2:00 / +3:00|
|Colorado /||France /|
|UTC -7:00 / -6:00||UTC +1:00 / +2:00|
|California /||U. Kingdom /|
|UTC -8:00 / -7:00||UTC +0:00 / +1:00|
Some countries do not adjust like most, to the exact hour of 60 minutes (1 hour), corresponding to the multiples of meridian of 15º.
To differentiate those countries from the rest, these intermediate time slots have been associated with 5 additional colors.
In this way, it can be easier to distinguish them from most countries that adhere to the 1-hour time slot.
Countries or localities that conform to a time slot of 30' are: Afghanistan- Chatham Islands - Eucla - India (Sri Lanka) - Iran - Lord Howe Island (in winter) - Myanmar - Newfoundland (St. John's) - Northern Territory of Australia - South Australia.
Eucla - Chatham Island - Nepal, adjusts to a 45 minute or 3/4 hour time slot.
Sorted by time slots from lowest to highest
|St. John's /||Iran /|
|UTC -3:30 / -2:30||UTC +3:30 / +4:30|
|Afghanistan||India / Sri Lanka|
|UTC +4:30||UTC +5:30|
|Nepal (in white)||Myanmar Burma|
|UTC +5:45||UTC +6:30|
|Eucla (W. Australia)||Broken Hill /|
|UTC +8:45||UTC +9:30 / +10:30|
|N.T. Australia (Map)||S. Australia /|
|UTC +9:30||UTC +9:30 / +10:30|
|Lord Howe /||Chatham Isl /|
|UTC +10:30 /+11:00||UTC +12:45 /+13:45|
All the countries that make the time change, advance the clock forward 1 hour during the summer period, and after a few months they go back that hour, with some exceptions, such as for example.
Lord Howe Island UTC +10:30 belonging to Australia, which is only 30' ahead and behind. With this, during the summer period, it equates the same time zone to UTC +11h. with the Australian Territories: New South Wales, Victoria and Tasmania using UTC +10h. in winter. Australia Map.