Timezones

Timezones

How many time zones are there?

Earth is divided into 24 time zones.

Why is Earth divided into time zones?

It takes about 24 hours to rotate once on its axis

Because Earth is constantly spinning, time is constantly changing

TimezonesHow are timezones divided?

Each timezone is about 15° wide, corresponding to longitude

However, some timezones have been adjusted in local areas

Why?

So that cities wouldn’t be split it half by a timezone!

Large countries often have several timezones

Timezones

Open your textbooks to p. 30

The figure at the bottom of the page shows international time zones.

When it is 12pm in England, what time is it in Madagascar?

If it is 3pm in Argentina, what time is it in Hawaii?

Calendar DatesWhen do we switch from one day to the next?

Each day ends at the stroke of midnight

Each time you travel through a time zone, you gain or lose time, until at some point, you gain or lose an entire day

International Date Line - 180°meridian - serves as the transition line for calendar days

When you travel west across the Date Line, you advance your calendar one day

When you travel east across the Date Line, you move your calendar back one day

Pull out a Blank Sheet of Paper

Use the figures on page 30 and 31.

1. When it is 10am in Atlanta, Georgia, what time is it in Los Angeles, California?

2. It’s 2pm in Denver, Colorado. What time is it in Chicago, Illinois?

3. If it’s 2pm in New York, New York, what time is it in Quito Peru?

4. If it is 3pm on Thursday, July 4 in Salt Lake City, Utah, What time and day is it in Tokyo, Japan?

5. If it’s 10am in Syracuse, New York (76° W longitude), What time is it in Athens Greece (24° E longitude)?

6. Would a person flying from Virginia to California have to set his or her watch backward or forward? Explain.