Time

All measurements of time are based directly on the

apparent movements of the sun.

Solar noon: when the sun is centered at its highest point in the sky on that

day.

Solar Day: the time from one noon to

the next noon

(midnight to midnight actually measures one day)

•For convenience we have adjusted the day to 24 hours,

although it is a little less

The Basis of the Time Zone: • The Earth like all circles is 360˚ around

• The Earth spins 360˚ in one day (24 hours)

• If we divide 360˚ by 24 hours in a day, we get 15˚ for every hour

The basis of Time Zones• Since the Earth moves 15˚every hour, Earth is

divided into 24 time zones that are 15˚ of longitude apart.

Time Zones• For convenience sake, states and countries do

not always divide the time zones directly along the lines of longitude

Think about this…

• Earth Rotates counterclockwise (so that means it rotates West to East)

• This means that the EAST experiences the day first…

• Time zones to the east are later in the day then time zones in the west

Time Zone Problems!!

1. If the time was 12:15 am in Los Angeles, California what time would it be in Bow, New Hampshire? 2. If it was 9:00 p.m. in New Hampshire, what time would it be in Miami, Florida? 3. About how many time zones would you pass through if you traveled 190 degrees around the earth?