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INTRODUCTION TO LATITUDE AND LONGITUDE

Essential Question: How do geographers describe location?

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Global Grid System

The globe is divided up into a global grid with lines of Latitude (parallels) and Longitude (meridians)
Latitude and longitude are both measured in degrees

Minutes and seconds or decimals for accuracy

When writing coordinates for a location, latitude is always before longitude (“la” before “lo” in the dictionary!)

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Latitude lines run east/west but they measure north or south of the equator (0°)�

The equator, Tropic of Cancer and Capricorn, and the Arctic and Antarctic Circles are important lines of latitude

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Latitude

Easy way to remember:

“flatitude”

OR

“laddertude”

Also called “parallels” because they never touch

Rungs on a ladder are flat but take you up (north) or down (south)

This is why latitude lines are either North or South

Latitude tells you how far you are from the equator (either north or south)

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Longitude

Lines that run north to south but they measure east to west
Tells you how far your are from the Prime Meridian
Unlike latitude lines, these all touch at the poles and are called “meridians”

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Important Meridians

Prime Meridian (0°)

International Date Line (180°)

Greenwich, England

Mostly in the Pacific Ocean

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First click: These are latitude lines in our grid. They run from east to west, but you use them to find your position north and south of the Equator. Which of these lines would be the Equator in our picture? (Click again and it will move).

Third click: These are longitude lines in our grid. They run from north to south, but you use them to find your position east and west of the Prime Meridian. Which of these lines would be the Primer Meridian in our picture? (click again and it will move).

Another important line of longitude is the International Date Line. This line is important because it is the point on the earth where the time and date change because of time zones. The International Date Line is at 180 degrees – opposite of the Prime Meridian. Which line on this map would be the International Date Line? (click again and they will move).

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How to Write Coordinates

When writing always write the latitude coordinate FIRST.

##^o N/S, ##^o E/W

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Application��N

W E

S

North America is in the Northern Hemisphere because it is north of the Equator. North America is in the Western Hemisphere because it is west of the Prime Meridian.

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TIME ZONES

Essential Question: What are time zones and how are they used?

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INTERNATIONAL DATE LINE�180°

SEPARATES 2 CALENDAR DAYS.

America to Asia – lose a day

Asia to America – gain a day

EAST INCREASE
WEST LESS

If you took a cruise on a ship, circumventing, or traveling around the entire planet, you would experience firsthand a phenomena that would help you understand the importance of an international dateline. An explorer by the name of Ferdinand Magellan did just that in the year 1519. Magellan along with 241 men set out to travel around the entire Earth. These men kept very careful records as they traveled. Yet, when they returned, they found that their calendars were off by one day with the calendars of everyone in their home countries. What happened? How did these men loose an entire day? The day was not lost all at once. It was lost little by little, as the traveled around the Earth. If you stay in one place, a day lasts 24 hours. However, if you travel the opposite direction of the rotation of the Earth, your day will be slightly longer than 24 hours, because you are traveling ahead of the setting sun. If you travel with the rotation of the Earth, your day will be slightly shorter than 24 hours, because you are traveling into the sunset.

At any one moment there are actually two days on the Earth at the same time. A new day begins at mid-night on the International Dateline. It travels around the Earth, until 48 hours later it ends back at the International dateline. If you were to travel across the International Dateline, the date would change either forward, or backward. This line actually lies in the middle of a time zone. This means that the hour on the clock would not change, as you crossed over, just the date.

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LONGITUDE AND TIME

The world rotates (spins) 360° in 24 hours.

360° / 24 hours = 15° per hour

The world has 24 time zones, each l5° apart.

THERE IS A 1 HOUR TIME DIFFERENCE FOR EVERY 15° OF LONGITUDE

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This pictures shows AMERICAN CITIES at night.

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Saguenay

Ottawa

Sept-Iles

Mexico City

Québec

Montréal

St.John

Those light are Boston, New York, Philadelphia and Washington.

Toronto

Detroit

Miami

Havana

Puerto Rico

Houston

Dallas

It’s still daylight in California

Thunder Bay

Port-au-Prince

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East Increase – West Less�(1 hr per l5°)

If it 9 p.m. at Position D, what time is it at position C? Position B?

If it is 1 p.m. at Position X, at which location is the time 5 p.m.