Motion of the Earth

Climates, Seasons, & Days

What do you know?

What do you know about the motion of the Earth & the effects it has on us.

Earth’s Motion

• Earth has two major types of motion• Earth’s Rotation• Earth’s Revolution

How Earth Moves

• Lets Demonstrate the difference between a Rotation & a Revolution

Earth’s Rotation

• The spinning of the Earth on its axis • the axis is the imaginary line that runs vertically through the

center of the Earth • rotates from East to West

• Rotation of the Earth produces 2 main effects:• Speed causes the length of a day to be about 24 hours• Causes daily changes from day to night

• At all times half of the Earth faces the sun, while the other half is in darkness

• Areas within the Artic & Antarctic circles experience several weeks of daylight or darkness depending on the time of year

Earth Revolving

Earth’s Revolution

• The movement of Earth around the sun• Earth’s orbit is the slightly elliptical path that it travels

around the sun• The sun is not in the center:

• Around January 3rd earth is about 147million km away (closer)• Around July 4th earth is about 152 million km away (farther)

• Revolution has 2 major effects:• The time it takes Earth to revolve around the sun once

defines the length of a year• It takes 365 ¼ days to make one complete revolution

• Every 4th year is leap year to make up for the extra day we gained• Earth revolves with a tilt of the axis

• The revolution causes the changing seasons

Earth’s Revolution

Changing Seasons

If we are closer in January than in July, why is it that we have are coldest days of the year during this time?

• Earth’s tilted axis combined with the revolution causes seasons to change

• Earth’s axis is at an angle of 23.5° to its orbit• The axis always points in the same direction as the Earth

orbits the Sun• The Northern hemisphere points toward the sun half of the year &

away from the sun for half the year• The tilt causes the Earth’s surface to receive different amounts of

solar energy throughout the year

Seasons on Earth

• Earth has seasons because it is tilted as it revolvesaround the sun.

Solstices

• A solstice is the day when the Sun reaches its greatest distance north or south of the equator• The day Earth is tilted most toward the sun • June 21st is the summer solstice (northern hemisphere)

• The most direct rays hit the Tropic of Cancer in the northern hemisphere causing the northern hemisphere to have warmer temperatures and more sunlight hours

• Longest day of sunlight for the year• Daylight gets a little shorter each day after the solstice

• Dec. 21st is the winter solstice (northern hemisphere)• The most direct rays hit the Tropic of Capricorn in the southern

hemisphere causing the northern hemisphere to have cooler temperatures and less sunlight hours

• Shortest day of sunlight for the year• Daylight hours get a little longer each day after the solstice

Equinox

• An equinox is the day the Sun’s rays are directly above the Earth’s equator.• During this time equal amounts of sunlight are received

all over the earth with the most direct rays hitting at 90° at the equator

• March 21st is the spring equinox (northern hemisphere)• September 22nd is the autumn equinox (northern

hemisphere)• Seasons are opposites in the Southern Hemisphere

Effects of Earth’s Revolution

Seasons at a Glance

Winter Begins(solstice)

December 21st or 22nd

Spring Begins(equinox)

March 20th or 21st

Summer Begins(Solstice)

June 21st or 22nd

Autumn Begins(Equinox)

September 22nd or 23rd

Animation

• revolution• Revolution• Extra Practice

• Click on view

Seasons on Earth

• The height of the sun above the horizon varies with the season.

Radiation from the Sun

• The hemisphere that is tilted toward the sun receives more daylight hours and absorbs more radiation from the sun

• The suns radiation strikes the earth surface at a higher angle when the hemisphere is tilted toward the sun• The higher the angle the more radiation the

earth absorbs creating warmer temperatures

Climatic Zones

• The amount of sunlight affects Climatic Zones• The latitude, distance north or south from the

equator, affects the temperatures that commonly occur in that area.• The further from the equator the less direct the suns

rays are• Theses yearly patterns cause weather patterns to occur

in different regions of the earth that create climates

Climatic Zones

Air Temperature by Month

World Temperature Zones

• Based on latitude, Earth’s surface can be divided into a tropical zone, two temperate zones, and two polar zones.

Biomes are large geographical areas with similar climates and ecosystems