Time Zones

TIME ZONES

EARTH ROTATION

•Axis – Invisible line through the center of the earth.

•Rotation – Earth spinning on it’s axis.

•Takes 24 hours.

CREATES A NEED FOR TIME ZONES

24 time zone - 1 for each hour

15 degrees per time zone (24 * 15 = 360)

Time Zones

• ​Because sunlight will reach different parts of the world at different times, the Earth is divided into Time Zones.

• A Time Zone is an area where all clocks are set to the same time.

• ​Earth has 24 Time Zones because Earth takes 24 hours to rotate one time.

Prime Meridian

o   0° longitude

o   Greenwich, England

o   Starting point for all lines of longitude

o   Everything is measured in distance (degrees) East or West of here

o   West = one hour less

o   East = one hour ahead

International Date Line (IDL)

o   Imaginary line through Pacific Ocean at 180 degrees longitude (opposite Prime Meridian)

o   Each new day begins here

o   New Year's Eve

Jagged Time Zones

o   follow national boundaries

o   consistent date/time for regions

Who Decides?

o   Time Zones are determined by each country.

o   Some countries don't fit with the standard hourly time zones

o   Examples include China, Iran, India, North Korea

Multiple Choice

if you cross a time zone line going east you must.....

• subtract an hour from your watch

• add an hour to your watch

Multiple Choice

How many time zones are there in the world?

• 24

• 12

• 6

• 48

Multiple Choice

Why aren't time zone boundaries completely straight?

• so they don't split cities, coutrires or buildings

• to allow for travel time

• for train and airplane schedules

• because of landforms

Multiple Choice

Places that are located to the West...

• Are at an earlier time

• Are at a later time

Multiple Choice

What causes day and night?

• the sun moving around the Earth

• the Earth moving around the sun

• rotation

• revolution

Multiple Choice

The international dateline measures _____________ degrees

• 100

• 90

• 180

• 360

U.S. Time Zones

o   west = one hour less (-) "west is less"

o   east = one hour ahead (+)

o   each time zone is a one hour difference

o   9 am in the Central time zone is 10 am in the Eastern time zone (one hour east/more) and 8 am in Mountain time zone (one hour west/less)

European Time Zones

​Move west subtract 1 hour

Move east add 1 hour

When 9 am in France, it is 8 am in Ireland and 10 am in Ukraine