Chapter 14 Section 2 What are time zones? Objective Use standard time zones to compare times around the world. Identify eight U.S. time zones.

Key Terms solar noon: time of day when the Sun is highest in the sky standard time: system whereby all places within a time zone all have the same time International Date Line: boundary formed where the first and twenty-fourth time zones meet

Solar Time The Sun can be used to tell time. Using the Sun to measure time is called solar time. Because Earth rotates, different places have solar noon at different times. For example, when it is solar noon in Philadelphia, it is 4 minutes after solar noon in New York and 17 minutes after solar noon in Boston.

What is a problem that is likely to arise using solar time? HYPOTHESIZE What is a problem that is likely to arise using solar time?

Standard Time Even though clocks allowed people to keep track of time, there was still a problem. Each region set its own time, and there was no way to coordinate between regions. This problem grew when railroads were built and people traveled more. A system would also help travelers schedule meetings in other towns.

Standard Time In 1884, an international agreement was reached that divided Earth’s surface into 24 time zones. Each of these zones was to be 15° of longitude wide. All places within a time zone would have the same time.

2. DESCRIBE What is standard time?

U.S. Time Zones The United States has eight time zones. These are Eastern Standard, Central Standard, Mountain Standard, Pacific Standard, Alaska Standard, Hawaiian Standard, Samoa Standard, and Atlantic Standard.

U.S. Time Zones As you move west, the time in each zone is one hour earlier than the previous zone. As a result, when it is noon in New York, it is 11:00 A.M. in Chicago. Time zones do not have straight boundaries. The boundaries were drawn this way to keep whole states or large neighboring cities in the same time zone.

If it is 12:00 noon in California, what time is it in Virginia? 3. CALCULATE If it is 12:00 noon in California, what time is it in Virginia?

World Time Zones There are 24 standard time zones in a day. The first time zone is on one side of the boundary called the International Date Line. The twenty-fourth time zone is on the other side. As you cross over the International Date Line, you either gain or lose 24 hours. If you were to travel west, you would have to move your calendar ahead one full day when you crossed the International Date Line.

4. INFER What happens to the date if you cross the International Date Line going east?

Classwork CHECKING CONCEPTS There are ___ time zones in the world. Using the Sun to measure time is ___. The 48 states in the continental United States have ___time zones. If you cross the International Date Line going east, you would ___ 24 hours. As you travel west, you move the clock ___ one hour for each time zone.

Classwork THINKING CRITICALLY 6. IDENTIFY: In which time zone is Texas located? 7. ANALYZE: If it is 3:00 P.M. in Florida, what time is it in Oregon? 8. CALCULATE: Suppose you leave California at 12:00 noon Pacific Standard Time and take a six-hour plane trip to Boston. When you land in Boston, what would the time be there? 9. IDENTIFY: In which time zone do you live?