Longitude and Time

Imagine clocks did not exist…..what would you base

time on?

Solar Time – Solar Noon –

Sunrise

Solar Noon

Sunset

What did the early clocks look like?

Sundial

Review Longitude Lines

Do students in California get up when you get up for school?

Time = Longitude!!

Earth’s Rotation

• Earth Rotates ___o

in 24 hours• 360o/24hrs =

__o per hour

Standard Time ZonesWhat is the amount of time difference

between each time zone?–1 hour–Every 15o longitude is a new time

zone.–How many time zones are there? –24 hours in one day… there are 24

time zones!

Map of 24 Hour Time Zones

•

                                                                                                                        

Determining Longitude

1st: -

A chronometer is a clock set to the

local time at Greenwich, just

outside of London.

2nd: - Local time best found at Solar Noon (12

noon)

Sextant

3rd: Multiply by -0/hr

4th: -

• If GMT is later in the day compared to local time – you are west

• If GMT is earlier in the day compared to local time - you are east

Prime Meridian

East sees daylight first!

West last to see daylight!

Example 1• GMT = 2 pm • Local Time = 12 noon• What is your longitude?

2 hours*15° = 30°2pm is later in the day than 12 noon -

30°W

Prime Meridian

The Prime Meridian is later in the day than local time.

2pm

12pm

• GMT = 8 am• Local Time = 12 noon • What is your Longitude?

Final Question• GMT = 10 pm• Local Time = 12 noon • What is your Longitude? http://www.polleverywhere.com/multiple_choice_polls/NTc3NDc4NTY1/web

Final Question• GMT = 10 pm• Local Time = 12 noon • What is your Longitude?

-* -° = -°-