Introduction to World GeographyMr. Healey

EquatorImaginary line that divides the earth into northern and southern hemispheres.It is expressed as 0° Latitude.

Equator

Northern Hemisphere

Southern Hemisphere

Prime MeridianImaginary line that divides the earth into eastern and western hemispheres.Greenwich, England = 0° Longitude.

Eastern

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Western

H

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Prime Meridian

Latitude Lines (Parallels)Used to locate places north or south of the equatorLines run parallel to the equatorTotal of 180 lines of latitude 90° North90° South

Longitude Lines (Meridians)Used to locate places east or west of the Prime Meridian.Lines run from the North Pole to the South Pole.Total of 360 lines of longitude180° East180° West

Longitude Lines and Time The distance between lines of latitude and longitude is approximately 70 miles. As the Earth revolves around the sun, different parts of the Earth are experiencing different times of day at the same time. For example, if it is twelve noon here, can the sun still be shining half-way around the world from our location? Of course the answer is NO! As the Earth rotates, both sides of the globe cannot be facing the sun at the same time. QUESTION: How do we tell what time it is around the world? ANSWER: We use lines of longitude to assist us.

Lines of longitude can also mark the hours of the day as the Earth rotates.Every 15° east or west is equal to one hour.If it is 12 noon at the Prime Meridian, what is the time at the other meridians?

15 E 30 E 90 E30 W90 W 15 W

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North Pole

South Pole

Major Latitude Lines

Equator = 0°

Tropic of Cancer = 23.5° North Arctic Circle = 66.5° North North Pole = 90° North

Tropic of Capricorn = 23.5° South Antarctic Circle = 66.5° South South Pole = 90° South

Major Latitude Lines

EQUATOR 0°

North Pole 90° North

Tropic of Cancer 23.5° North

Arctic Circle 66.5° North

Tropic of Capricorn 23.5° South

Antarctic Circle 66.5° South

South Pole 90° South

Major longitude LinesPrime Meridian = 0°International Date Line = 180°

SeasonsAs the Earth revolves around the Sun, it is tilted at 23.5° angle.

Because of the Earth’s revolution and its tilt, different parts of the Earth receive the direct rays of the sun for more hours of the day at certain times of the year.

This causes the changing of the seasons on the Earth.

SummerSpring

WinterFall

Vernal (Spring) Equinox Occurs when the sun is directly over the Equator. (March 21st ).Equal amount of day and night during a 24-hour period.

Sun’s direct rays strike the Equator

Earth is tilted at 23.5 degrees

North Pole 90° N

South Pole 90° S

Equator

Summer Solstice Occurs when the sun is directly over the Tropic of Cancer (June 21st).Marks the longest day of the year in the northern hemisphere.New York City sees approx. 15 hours of light and 9 hours of dark.Sunrise = 5:25amSunset = 8:30pm

Sun’s direct rays strike the Tropic of Cancer

North Pole 90° N

South Pole 90° S

Northern Hemisphere facing sun’s direct rays

Tropic of Cancer 23.5° North

Autumnal EquinoxOccurs when the sun is again directly over the Equator (Sept. 23rd).Equal amount of day and night during a 24-hour period.

Sun’s direct rays strike the Equator

Equator

North Pole 90° N

South Pole 90° S

Earth is tilted at 23.5 degrees

Winter SolsticeOccurs when the sun is directly over the Tropic of Capricorn (December 21st).Marks the shortest day of the year in the northern hemisphere.New York City sees the reverse in hours of day and night from the summer solstice.

Sun’s direct rays strike the Tropic of Capricorn

North Pole 90° N

South Pole 90° S

Tropic of Capricorn 23.5°

South

Northern Hemisphere tilted away from sun

AphelionThe point at which the earth is farthest from the sun during its orbit.

Occurs around July 3 when the earth is 94.5 million miles away.

PerihelionThe point at which the earth is closest to the sun during its orbit.Occurs around January 4 when the earth is 91.4 million miles away.