1. -Time is based on longitude lines.
TIME AND LONGITUDE
-Time is based on longitude lines.

2. TIME AND LONGITUDE:
-time is based on longitude lines so…..
-every 15o of longitude equals one hour
and every time zone is 15o wide
The reason:
-the Earth rotates 15o/hour from west to east

3. It’s easy really….. The Earth is a 3600 sphere.
There are 24 hours in a day.
3600 = 150/hour
24 hours

4. -the time between two longitude lines is constant, so the time won’t change until you are totally past the 15o longitude line

5. -as you move due north or due south the time remains the same
as you move due east or due west the time will change
Here’s how:
-as you move east the time gets 1 hour later for every 15o of longitude you cross.
-As you move west the time gets 1 hour earlier for every 15o of longitude you cross.

6. As you go east time will increase
As you go west time will be less

8. DIFFERENT TIMES -Solar Noon-when the Sun is highest in the sky
ex: it is the same for each longitude line
-Solar Time-time based on the Sun’s location within a time zone
-Clock Time-all clocks are set to the same time within a time zone
-Greenwich Mean Time (GMT)-the time at the Prime Meridian
-Greenwich, England is where the official time is
kept
-it is kept on a clock called a chronometer

9. International Date Line
this is the 180o longitude line
-as you cross the date line going west you add a day
-as you cross the date line going east you subtract a day

11. The continental U.S. has 4 time zones.

12. WHY DO THE TIME ZONES WIGGLE SO MUCH?