The continent of Africa consists of four time zones. The countries that border the Atlantic Ocean in the northern portion of the continent, which includes Ghana, make up one time zone. Accra, Ghana's capital city, is in the Greenwich Mean Time zone. It takes its name from Greenwich England. It is the baseline for all time zones and is still considered to be standard time in the world.
Portland Oregon is located on the Pacific Ocean and resides in the most western of the four time zones in the continental United States. Portland sits below Mt. Hood and next to the Columbia and Williamette rivers. Portland's time zone, along with all but the most eastern portion of Oregon, is known as Pacific Standard or Daylight Time, depending upon the time of the year.
Determining time differences requires knowledge of time zones and the hourly differences from GMT. Because Accra, Ghana is located in GMT, a time zone that includes England, Iceland and the countries of northwest Africa, it is easy to make the calculation as all time zones are expressed in hourly differences from GMT. Portland Oregon, being in PST, is eight hours different from GMT in Accra. Noon in Accra is 4 a.m. in Portland when both observe standard time. To complete the time difference calculation between Accra and Portland, the effects of daylight savings time must be considered.
Daylight Savings Time is the practice of moving the clocks ahead one hour during portions of the spring, summer and fall in order to transfer daylight time from the morning to evening. Since not all locations use it, you must determine whether or not a particular city is observing it to determine time differences. Accra does not observe daylight savings time. Portland observes daylight savings time, changing its time on the second Sunday in March and reverting back to standard time on the first Sunday in November. During that interval Accra and Portland have a time difference of seven hours, making noon in Accra 5 a.m. in Portland.
