The 360 longitudes of the globe, has been divided into groups of 15 longitudes. This makes a total of 24 groups. Each group of 15 longitudes forms a time zone or a belt. The world is therefore divided into 24time zones or belts. That is why there are 24 hours in one day. Every time zone of 15° of longitude has only 1 local time.

Standard Time

This is the local time kept within each time zone. It is a common time; it is kept by a group of 15 longitudes found in one time zone. The standard time of each time zone is 1hour different from that of the next zone. Two towns found on different longitudes, will have one standard time, if they belong to the same kind zone.

Some countries have more than one time zone. Eg: U.S.A and Canada cover 5 time zones and Australia 3time zones. They have more than 1 time zone because of their large area.

Exercices

1. If the local time of Moutoundou (Cameroon) on longitude 15°E is 12am. What is the local time in Montreal (Canada) on longitude 75°W.?
2. What is the local time in Monrovia 10°W, 6°N when local time in Washington DC is 75°W, 35°N is 11:00am.
3. The local time of G.M.T is 4pm. What is the longitude of Los Angeles whose local time is 8am?
4. The time of G.M.T is 12noon and in Saudi Arabia it is 5pm. On which longitude is Saudi Arabia found?