1. Warm Up
Why do you think the days are shorter in Winter and longer in summer?

2. Hemispheres The earth is a sphere.
It can be divided into two hemispheres.

3. Equator – imaginary line that divides the northern and southern hemispheres.
Northern Hemisphere
Northern
Southern
Southern Hemisphere

4. Seasons
Why do we have
seasons?

5. Reasons for the Seasons
The earth’s axis is tilted
The earth’s axis always points in the same direction
The earth travels around the sun
Direct sunlight has more heat than sunlight at an angle.

6. Tilt of the Earth
The Earth is always leaning, or tilted, in the same direction This is important!
Hey, I’m leaning to one side!

7. The Earth’s axis is tilted 23.5°
No tilt
23.5°

8. Wow, it took a whole year to revolve around the Sun!
It takes one year for the Earth to revolve around the Sun.
Wow, it took a whole year to revolve around the Sun!
March, April, May
June,
July,
August
December, January,
February
September, October, November

9. Seasons
The amount of Sunshine we get changes as the Earth travels around the Sun.

10. Seasons
Look at the diagram and see how much Sun the person on the Earth is getting in each season.
Spring
Summer
Winter
Find the equator in each season. Then find the northern hemisphere.
Fall

11. Summer Where is it summer in the northern hemisphere???

12. Summer The hemisphere that is tilted towards the sun has summer.
This shows summer in the northern hemisphere where we live.

13. Summer
When your part of the Earth is tilted toward the Sun, the days are longer and hotter. It is summer.

14. Winter Where is it winter in the northern hemisphere???

15. Winter
In winter, that same part of the Earth is tilted away from the Sun.

16. Winter
When it is winter where you live, your part of the Earth is tilted away from the Sun.
Your part of the Earth gets less Sunshine so it is colder.

17. Seasons
In the winter the days are short and the nights are long.

18. Opposite Seasons Each hemisphere has opposite seasons. Spring Summer
Winter
Find the equator in each season. Then find the northern hemisphere.
Fall

19. We have seasons because Earth is
TILTED TILTED TILTED TILTED TILTED
We have seasons because Earth is
T I L T E D

20. If the Earth’s axis was not tilted, we would not have seasons.
What if…
If the Earth’s axis was not tilted, we would not have seasons.

21. Christmas Around the World
On Christmas day it is winter in the USA and Europe. On Christmas day it is SUMMER in Australia and Africa.
USA - Christmas
Australia - Christmas

22. Christmas Around the World

23. Sun’s Angle
The angle that the sun hits the Earth plays a part in the seasons. Look at the angle at which the sun hits the hemisphere in each season. The more direct the ray, the hotter it is.
Hottest
Cool
Cool
Cold
Warm

24. Look at which hemisphere the sun is hitting in each season
Look at which hemisphere the sun is hitting in each season. The blue is the Northern Hemisphere where you live. The green is the Southern hemisphere where Australia is located.

25. Reasons for the Seasons
The earth’s axis is tilted
The earth’s axis always points in the same direction
The earth travels around the sun
Direct sunlight has more heat than sunlight at an angle.

26. Solstices – occur when the sun is the greatest distance north or south of the equator.
December 21 – Winter Solstice (in Northern Hemisphere)
June 21 – Summer Solstice (in Northern Hemisphere)

27. Equinoxes – occur when days and nights are the same length.
September 22 – Autumnal Equinox (in the Northern Hemisphere)
March 20 – Vernal Equinox (in the Northern Hemisphere)