SeasonsSeasonsBenchmark Benchmark SC.8.8.3 Describe

how the Earth's motions and tilt on its axis affect the seasons

and weather patterns

SWBATSWBAT

SWBAT explain the factors that influence SWBAT explain the factors that influence seasonal change and identify the seasons of seasonal change and identify the seasons of different geographic regions.different geographic regions.

Benchmark Benchmark SC.8.8.3 Describe how the Earth's motions and tilt on its axis affect the seasons and weather patterns

Vocabulary LessonVocabulary Lesson

Before we begin our discussion on ‘Seasons’ Before we begin our discussion on ‘Seasons’ we need to understand the difference we need to understand the difference

between two terms.between two terms.

REVOLUTION REVOLUTION andand

ROTATIONROTATION

Vocabulary LessonVocabulary Lesson

REVOLUTION – when a moon REVOLUTION – when a moon or planet travels once or planet travels once

around another object, this around another object, this is a revolution.is a revolution.

Example: A complete trip of Example: A complete trip of the Earth around the sun the Earth around the sun

Model of the SeasonsModel of the Seasons

Quick Challenge Question: Name Quick Challenge Question: Name ONE limitation of the model ONE limitation of the model

belowbelow..

Which planet has the Which planet has the SHORTEST revolution? SHORTEST revolution?

Longest?Longest?

Vocabulary LessonVocabulary Lesson

ROTATION – a circular ROTATION – a circular movement of an object movement of an object

around a center (or point) around a center (or point) of rotation. of rotation.

Example: When the Earth Example: When the Earth makes a complete trip on makes a complete trip on its axis from west to eastits axis from west to east

RotationRotation

How about a song to help How about a song to help remember the difference?remember the difference?

SeasonsSeasons

Outside the Tropical zone, most places have Outside the Tropical zone, most places have four seasons: winter, spring, summer, and four seasons: winter, spring, summer, and autumn. autumn.

The North and South Hemisphere have The North and South Hemisphere have opposite seasons.opposite seasons.

Hmmm…Hmmm… Why would the Northern and Southern Why would the Northern and Southern

Hemisphere have opposite seasons?Hemisphere have opposite seasons?

Yes! Tilted Axis of Yes! Tilted Axis of EarthEarth

Seasons are caused by the tilt of Earth’s Seasons are caused by the tilt of Earth’s axis as the Earth travels around the Sun. axis as the Earth travels around the Sun.

So when the Northern Hemisphere is tilted So when the Northern Hemisphere is tilted toward the Sun it gets toward the Sun it gets __________________________and while the __________________________and while the Southern Hemisphere is tilted away from Southern Hemisphere is tilted away from the Sun _________________________________the Sun _________________________________

Good… so this is what the Good… so this is what the earth’s axis looks like, right?earth’s axis looks like, right?

WRONG!

Earth’s Axis: Not So Earth’s Axis: Not So Straight!Straight! The earth’s axis is The earth’s axis is tiltedtilted about about 23.523.5 degreesdegrees

from vertical.from vertical.

23.5˚ Axis

Earth’s Axis: Not So Earth’s Axis: Not So Straight!Straight! The earth’s axis is The earth’s axis is tiltedtilted about about 23.523.5 degreesdegrees

from vertical.from vertical.23.5˚ Axis

Look at the Polar zones Look at the Polar zones at the Arctic and at the Arctic and Antarctic circle Antarctic circle

The Polar The Polar ExperienceExperience

When it is Summer in the Northern When it is Summer in the Northern Hemisphere, the Polar zone in the Northern Hemisphere, the Polar zone in the Northern Hemisphere experiences daylight for 24 hours Hemisphere experiences daylight for 24 hours a day. a day.

Based on the picture, the Polar zone in the Based on the picture, the Polar zone in the Southern Hemisphere is tilted away from the Southern Hemisphere is tilted away from the Sun, so it will get total darkness 24 hours a Sun, so it will get total darkness 24 hours a day. day.

The opposite happens when it is Winter in the The opposite happens when it is Winter in the Southern Hemisphere.Southern Hemisphere.

How the Earth moves How the Earth moves around the Sunaround the Sun

As the Earth travels around the sun it keeps As the Earth travels around the sun it keeps the same tilt. the same tilt. So, when the North Pole is tilted toward the Sun So, when the North Pole is tilted toward the Sun

in the summer it is tilted away from the Sun in in the summer it is tilted away from the Sun in the winter. the winter.

Angle of SunlightAngle of Sunlight

The amount of direct sunlight is The amount of direct sunlight is CONTINGENT on the tilt of the axis. CONTINGENT on the tilt of the axis.

As direct rays of sunlight increase, As direct rays of sunlight increase, temperature _____________________temperature _____________________

Let’s take a closer Let’s take a closer look:look: