Tilt of the Earth

1. What is the difference between rotation and revolution ?

2. What causes the earth’s seasons ?

3. What is the position of earth during each season?

4. How does Earth’s tilt cause temperature differences in the seasons ?

Rotation vs. Revolution

• The Earth ROTATES on its axis

• ROTATION mean to “spin”• An axis is an imaginary

line that goes through the center of the planet

• The earth is TILTED 23.5° from the vertical position of the axis

• The Earth REVOLVES (revolution) around the sun

• REVOLUTION means to “move around an object”

• One revolution takes approximately 365 days ( 1 year)

What causes the Earth’s Seasons ?

• The earth is divided by the equator into two halves called hemispheres ( North and South)

• The seasons are not the same on all parts of earth at the same time (when it is winter in the Northern Hemisphere, it is summer in the Southern Hemisphere)

• Earth’s revolution + (plus) the way the Earth tilts on its axis causes the seasons.

• The sun’s rays strike Earth unevenly – at different angles at different times of the year.

Position of Earth

• When the Northern Hemisphere tilts towards the sun = summer. • At the same time, its winter in the Southern Hemisphere• When the Northern Hemisphere tilts away from the sun = winter. • At the same time, its summer in the Southern Hemisphere

• Summer in Northern Hemisphere, Winter in Southern Hemisphere• Winter in Northern Hemisphere, Summer in Southern Hemisphere• Fall in Northern Hemisphere, Spring in Southern Hemisphere• Spring in Northern Hemisphere, Fall in Southern HemisphereThe seasons are always opposite in Earth’s Northern and Southern Hemispheres.

Temperature and Daylight

• The sun’s rays deliver the most energy when Direct

• When its Summer in an area, the sunlight is More directly

• The area receives Direct Energy from the sun

• During Winter, certain areas receive the sun’s rays at an angle

• When its Winter in an area, the sunlight is Less direct

• The area receives energy from the sun at an angle

The Causes of the Different Seasons

The sun’s rays strike Earth unevenly- at different angles at different times of the yearNear the equator, the sun’s rays hit DIRECTLYAT the poles, the sun’s rays hit AT AN ANGLE

Temperature and Daylight

• The amount of daylight also changes with the seasons.– Summer= more hours of daylight, so the sun heats Earth’s surface longer

( temperatures higher)– Winter = less hours of daylight, so the sun heats Earth’s surface for a

shorter amount of time ( temperatures lower)– In the Northern Hemisphere, from Dec. 21st to June 21st the period of

daylight gets longer, from June 21 to Dec. 21st, the period of daylight gets shorter

• Many parts of the earth do not have distinct seasons– Places near the equator receive direct sunlight all year long, so

temperatures remain high– The north and south poles get less direct sunlight from farther poles, so

even in summer, these places are still cold

Again- The Seasons