What causes seasons on earth

What causes seasons on Earth for elementary students.

1. What Causes Seasons on What Causes Seasons on
Earth?Earth?
By Nick SouthernBy Nick Southern

2. Michigan StandardsMichigan Standards
•E.ES.M.6 Seasons- Seasons result
from annual variations in the
intensity of sunlight and length of
day due to the tilt of the axis of the
Earth relative to the plane of its
yearly orbit around the sun.

3. Key VocabularyKey Vocabulary
•RotationRotation
•RevolutionRevolution
•AxisAxis

4. AxisAxis
•Axis – an Axis – an
imaginary imaginary
line which line which
the earth the earth
turns turns
aroundaround
•The earth is The earth is
tilted at tilted at
about 23.5 about 23.5
degrees.degrees.
http://upload.wikimedia.org/wikipedia/commons/6/61/AxialTiltObliquity.png

5. RotationRotation
•Rotation – turning Rotation – turning
around on an axisaround on an axis
•It takes the earth It takes the earth
about 24 hours to about 24 hours to
complete one rotation complete one rotation
around it’s axis. This around it’s axis. This
is also known as a is also known as a
day.day.
http://upload.wikimedia.org/wikipedia/commons/3/30/Globespin.gif

6. RevolutionRevolution
•Revolution – one object Revolution – one object
traveling around another traveling around another
in a circular or elliptical in a circular or elliptical
patternpattern
•It takes approximately It takes approximately
365 days for the earth to 365 days for the earth to
make one revolution make one revolution
around the sun. This is around the sun. This is
also known as a year.also known as a year.

7. What is a season?What is a season?
•A season is a subdivision of a year.A season is a subdivision of a year.
•We have four seasons on earth: winter, We have four seasons on earth: winter,
spring, summer, and fallspring, summer, and fall
•During seasons, hours of daylight and During seasons, hours of daylight and
weather may vary greatly depending on weather may vary greatly depending on
your location on Earth.your location on Earth.

8. So What Causes Seasons?So What Causes Seasons?
•There are two major causes for seasons There are two major causes for seasons
on Earth.on Earth.
–1 – the tilt of the earth on it’s axis1 – the tilt of the earth on it’s axis
–2 – position of the earth in relation to the sun 2 – position of the earth in relation to the sun
(revolution)(revolution)

9. WinterWinter
•We are going to focus on the We are going to focus on the
seasons in the Northern seasons in the Northern
Hemisphere (that’s where we Hemisphere (that’s where we
live).live).
•During winter, the earth is During winter, the earth is
titled away from the Sun.titled away from the Sun.
•This results in the Northern This results in the Northern
Hemisphere not getting strong, Hemisphere not getting strong,
direct rays from the Sun. This direct rays from the Sun. This
is what causes winter.is what causes winter.
•A cool fact is we are actually A cool fact is we are actually
closer to the Sun in the winter closer to the Sun in the winter
than in the summer.than in the summer.
•The amount of night hours The amount of night hours
exceeds daylight.exceeds daylight.

10. SummerSummer
•During summer in the During summer in the
Northern Hemisphere, the Northern Hemisphere, the
earth is tilted towards the earth is tilted towards the
Sun.Sun.
•This results in the This results in the
Northern Hemisphere Northern Hemisphere
getting direct rays from getting direct rays from
the Sun.the Sun.
•The amount of daylight The amount of daylight
exceeds the amount of exceeds the amount of
night hours.night hours.

11. Spring and FallSpring and Fall
•In the spring and fall In the spring and fall
seasons, seasons,
temperatures are temperatures are
generally mildgenerally mild
•Daylight and Daylight and
nighttime hours are nighttime hours are
almost equalalmost equal

12. Southern HemisphereSouthern Hemisphere
•We have already explored seasons in the We have already explored seasons in the
Northern Hemisphere.Northern Hemisphere.
•In the Southern Hemisphere, the seasons In the Southern Hemisphere, the seasons
are opposite.are opposite.

13. ExceptionsExceptions
•In tropical regions –those located around the In tropical regions –those located around the
equator do not received the four seasons. equator do not received the four seasons.
•Their “seasons” are wet and dry.Their “seasons” are wet and dry.
•In polar regions, during their winter, they may In polar regions, during their winter, they may
only receive a few hours of daylight each day only receive a few hours of daylight each day
and in the summer, only a few hours of and in the summer, only a few hours of
darkness.darkness.
•This is because they are either tilted towards the This is because they are either tilted towards the
Sun the most or they are tilted away from the Sun the most or they are tilted away from the
Sun the farthest.Sun the farthest.

14. SeasonsSeasons
http://en.wikipedia.org/wiki/File:Seasons1.svg

15. Video ClipsVideo Clips
•Seasons Aren’t Dictated By Closeness to the SunSeasons Aren’t Dictated By Closeness to the Sun
•How Earth’s Tilt Causes SeasonsHow Earth’s Tilt Causes Seasons

16. QuizQuiz
•What are the two factors which cause the What are the two factors which cause the
seasons on Earth?seasons on Earth?
•Are we closer to the Sun in the winter or Are we closer to the Sun in the winter or
summer?summer?

17. SourcesSources
•http://www.dictionary.comhttp://www.dictionary.com
•http://upload.wikimedia.org/wikipedia/commons/3/30/Globespin.gifhttp://upload.wikimedia.org/wikipedia/commons/3/30/Globespin.gif - Animated Earth - Animated Earth
spinning on axis.spinning on axis.
•http://upload.wikimedia.org/wikipedia/commons/6/61/AxialTiltObliquity.pnghttp://upload.wikimedia.org/wikipedia/commons/6/61/AxialTiltObliquity.png - Image - Image
of Earth on axisof Earth on axis
•http://en.wikipedia.org/wiki/File:Seasons1.svghttp://en.wikipedia.org/wiki/File:Seasons1.svg – Image of Earth in Relation to the sun – Image of Earth in Relation to the sun
•http://www.khanacademy.org/science/cosmology-and-astronomy/v/seasons-aren-t-dictated-by-closeness-to-sunhttp://www.khanacademy.org/science/cosmology-and-astronomy/v/seasons-aren-t-dictated-by-closeness-to-sun
- Video Clip - Video Clip
•http://www.khanacademy.org/science/cosmology-and-astronomy/v/how-earth-s-tilt-causes-seasonshttp://www.khanacademy.org/science/cosmology-and-astronomy/v/how-earth-s-tilt-causes-seasons
- How Earth’s Tilt Causes Seasons - How Earth’s Tilt Causes Seasons