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Earth ScienceSection 2.1 – Latitude and Longitude

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Students will be able to:◦ Define cartography◦ Describe the difference between latitude and

longitude.◦ Explain why it is important to give a city’s

complete coordinates when describing its location.

◦ Describe and locate the equator◦ Describe and locate the Prime Meridian◦ Describe and locate the International Date Line◦ Explain why there are different time zones from

one geographic area to the next.

Objectives

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cartography equator Latitude longitude prime meridian International Date Line

Vocabulary

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The science of map making is called cartography Maps are flat models of three-dimensional objects.

Cartography

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Cartographers put a series of grid lines over the map of the Earth, to allow them to find specific locations.

Grids Imposed by Cartographers

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This is the horizontal line around the center of the Earth.

Equator

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The equator divides the Earth into the north and south hemispheres.

North and South Hemispheres

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Lines parallel to the equator are called lines of latitude.

These lines are either north of the equator (degrees north) or south of the equator (degrees south)

Latitude

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The value in degrees of each line of latitude is determined by measuring the imaginary angle created between the equator, the center of Earth, and the line of latitude.

Each degree of latitude is 111 km on the surface of the Earth.

Latitude

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The lines of longitude are defined by the Prime Meridian (0˚ longitude)

Prime Meridian

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The location of the Prime Meridian was decided by astronomers in 1884, and goes through the Royal Naval Observatory in Greenwich, England, and extends to the North and South Poles.

Prime Meridian

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The Prime Meridian divides the Earth into the east and west hemispheres.

East and West Hemispheres

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Latitude measures degrees east or west of the Prime Meridian.

Unlike lines of longitude, these are not parallel, and meet at the poles.

Lines of longitude, also called meridians, are semicircles that extend vertically from pole to pole.

Longitude

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Why can’t we determine a value in km on the surface of the Earth for each degree of longitude?

Longitude

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The degree value of each line of longitude is determined by measuring the imaginary angle between the prime meridian, the center of Earth, and the line of longitude.

Longitude

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This grid system is used to locate specific locations on the Earth. Notice – each measurement has degrees and direction.

The Grid

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Both latitude and longitude are needed to locate positions on Earth precisely.

Using Coordinates

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Time Zones

Go east – later, go west - earlier

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Why are there 24 time zones?

How big is each time zone?

Why are the time zone lines not perfectly straight?

How many times zones are in the U.S.?

What are the names of the major time zones in the U.S.?

Size of Time Zones

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The International Date Line is at 180˚ Longitude◦ This is the transition

line between calendar days.

◦ Going East to West – gain 1 day.

◦ Going West to East – lose 1 day.

The International Date Line

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The International Date Line

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Variations in Time Zones - US

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Variations in Time Zones

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Countries Following DST – 2010/2011

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Day/Night 11:42 AM 3/9/2011