1. Science Lee County Adult and Community Education
GED Online Week One
Science
Lee County Adult and Community Education

2. Review of class assignments
3 weekly webinars
Math (only attend one math webinar per week)
Reading/Language Arts
Science/Social Studies
You must submit a summary of the webinar to your teacher if you miss the live webinar
3 weekly webinar assignments
Math (only complete the math assignment that corresponds to your webinar)
assignments to your teacher
6 hours on learn.aztecsoftware.com

3. Students Viewing Recording
If you are watching the recording of this webinar, you must submit a one paragraph summary of this webinar to your teacher.

4. Website for Webinars and Assignments

5. Please label all assignments
Reminder
To earn the correct credit-
Please label all assignments
Label homework by subject and week number
Label Webinars by subject and week and state that it is a webinar summary!
If submitting assignments by picture, please check for clarity before sending.

6. The Reason for the Seasons

7. The Reasons for the Seasons
The 23.5 degree tilt of the earth axis
AND
The revolution of Earth around the Sun
The number 23.5 shows up often in explaining
the changes with the sun throughout the year.

8. Earth’s Seasons The Earth is Tilted Most globes show the axis tilted
perpendicular
to orbit plane
The Earth is Tilted
23½°
Most globes show the axis
tilted
axis
orbit plane

9. What is not a reason for the seasons?
The earth is closer to the Sun?
NO!
Actually, the Earth is farthest from the Sun in July and closest to the sun in January!

10. What causes most areas on Earth to experience seasons?
The explanation of the beautiful changes that occur on Earth from season to season lies in the movement and position of the Earth in space.
Let’s go into space to examine these positions and movements and discuss their role in seasonal changes.

11. Do you know what the red line running through the Earth represents?
The red line is the equator. The equator is an imaginary line that separates the Earth into two halves. These halves are known as hemispheres.

12. The area above the equator is known as the Northern Hemisphere.
The area below the equator is known as the Southern Hemisphere.

13. In order to understand the seasons, you must first understand that the Earth is rotating in space. Rotation is the spinning of objects in space.
At any given time, half of the Earth is facing the Sun. That half of the Earth is experiencing day time. The other half is facing away from the Sun and is experiencing night time.

14. As Earth rotates/spins, any location on Earth moves through sunlight/day and darkness/night.
If Earth’s rotation causes day and night, how long does it take Earth to rotate around one time? How long does it take to get from the beginning of one day to the beginning of the next day?
It takes 24 hours to get through the light and dark before starting a new day.
24 hours in a day isn’t a number that someone just made up. 24 hours is how long it takes the Earth to completely rotate (spin around) one time.

15. The blue arrow running from the North Pole to the South Pole through the center of the Earth is Earth’s axis of rotation.
The axis of rotation is an imaginary line that an object in space spins around.

16. The main reason for the seasons is that the Earth’s axis of rotation is tilted. The Earth isn’t straight up and down as pictured below.
It is positioned and rotates at a tilt.
This is how the Earth is actually positioned.

17. In this picture, you can see that the North Pole and the Northern Hemisphere are TILTED AWAY FROM the Sun.
What season do you think the Northern Hemisphere is having when it is tilted away from the Sun?
The Northern Hemisphere is having winter.

18. If we look at the Earth a little closer, we can see why.
Light=daytime
dark=night time
Being tilted away means more of the Northern Hemisphere is shadowed. This means longer nights and shorter days. Have you ever noticed that it gets dark much earlier in the winter?

19. Obviously, when you’re not facing the Sun, it is generally cooler than it is during the day when you are facing the Sun. This means cooler, winter temperatures.
light=daytime
dark=night time
Another cause for cooler temperatures is the angle of the light that is hitting the Northern Hemisphere. Direct sunlight is hotter than light at an angle. Look at where most of the direct sunlight is hitting the earth.

20. The most direct sunlight is hitting in the Southern hemisphere
The most direct sunlight is hitting in the Southern hemisphere. The Northern Hemisphere gets light at an angle.
Light at an angle is less concentrated and cooler. This also contributes to the Northern Hemisphere’s cooler temperatures in the winter.

21. In summary, winter happens in the Northern Hemisphere when it is tilted away from the Sun.
This causes shorter days with less sun. It also means that the sunlight hits at an angle which is less concentrated and cooler.

22. What month would it be if the Northern Hemisphere is experiencing winter?
It would be December. That’s when the winter season begins in the NORTHERN Hemisphere.
But what about the Southern Hemisphere?

23. Notice that in December, when the Northern Hemisphere gets less sunlight, the Southern Hemisphere actually gets more sunlight.
The sunlight is also striking them more directly. So what season does the Southern Hemisphere have in December?
December is summer time if you live in the Southern Hemisphere.

24. This time of year is known as the December Solstice
This time of year is known as the December Solstice. A solstice is a time when sunlight is at a maximum in one hemisphere and a minimum in the other.
Since the Northern Hemisphere is getting minimum sunlight, December is known as their winter solstice. The Southern Hemisphere gets maximum sunlight, so December is their summer solstice.

25. If the Earth stayed in this position, the Northern Hemisphere would have a permanent winter. Of course, the Southern Hemisphere would have never-ending summer. However, the Earth doesn’t stay in this position. The Earth revolves/orbits around the Sun.
A revolution/orbit is the movement of one object in space going around another because of gravity.

26. The Earth revolves around the Sun once every year (365 days)
The Earth revolves around the Sun once every year (365 days). As it revolves, it stays tilted in the same direction in space. From this view, it stays tilted to the left.
Now watch what happens as Earth revolves to the opposite side of the Sun.

27. Notice that the Northern Hemisphere is still tilted to the left
Notice that the Northern Hemisphere is still tilted to the left. Being tilted to the left also means that the Northern Hemisphere is now tilted toward the Sun
What season does the Northern Hemisphere have when it is tilted toward the Sun?
Summer!

28. Look at the diagram on the next slide
Look at the diagram on the next slide. Notice how the Earth is always tilted in the same direction. As the Earth revolves, the part of Earth tilted toward the Sun changes.

30. If we look at the Earth a little closer, we can see why.
Dark = night time
Light= day time
First, you will notice that being tilted toward the Sun means more of the Northern Hemisphere is in light. This means longer days and shorter nights. Have you ever noticed that it stays light much later in the summer?

31. Obviously, when facing the Sun, it is generally warmer than it is during the night when you are not facing the Sun. This means warmer, summer temperatures.
dark=night time
Light=daytime
Another cause of warmer temperatures is the angle of the light that is hitting the Northern Hemisphere. Direct sunlight is hotter than light at an angle. Look at where most of the direct sunlight is hitting the Earth.

32. The most direct sunlight is now hitting in the Northern Hemisphere
The most direct sunlight is now hitting in the Northern Hemisphere. The Southern Hemisphere gets light at an angle.
The direct light striking the Northern Hemisphere is more concentrated and warmer. This also contributes to the warmer temperatures in the summer.

33. The Northern Hemisphere’s summer happens when it is tilted toward the Sun
This causes longer days with more Sun. It also means that the sunlight that the Northern Hemisphere gets hits more directly and is more concentrated and warmer.

34. What month would it be when the Northern Hemisphere is tilted toward the sun and is experiencing summer?
It would be June. June is when summer starts in the Northern Hemisphere.

35. What season is it in the Southern Hemisphere in June?
It would be winter. That’s because the Southern Hemisphere has shorter days, and receives sunlight at an angle. Remember, sunlight at an angle is less concentrated and cooler.

36. June is the summer solstice for the Northern Hemisphere.
That would make it the winter solstice in the Southern Hemisphere.

37. Why do we have seasons? Review
Seasons are the result of the tilt of the Earth's axis.
Earth’s axis is tilted 23.5°.
This tilting is why we have seasons like fall, winter, spring, summer.
The number of daylight hours is greater for the hemisphere, or half of Earth, that is tilted toward the Sun.

38. Solstices Review
Solstices occur twice a year, when the tilt of the Earth's axis is oriented directly towards or away from the Sun, causing the Sun to appear to reach its northernmost and southernmost extremes.
Winter solstice is the shortest day of the year. In the Northern Hemisphere. It occurs on December 21 and marks the beginning of winter.
The Summer Solstice is the longest day of the year. It occurs on June 21 and marks the beginning of summer.

39. To Sum It All Up…..
The seasons make up a pattern that repeats year after year. The seasons result from Earth’s tilt and revolution around the sun. Although Earth’s tilt on its axis stays the same, its tilt, or orientation, toward or away from the sun changes during the year. During winter in the northern hemisphere, for example, Earth is tilted its farthest away from the sun. The sun’s energy is less direct, and temperatures are cooler.

40. Let’s answer these questions..
The northern hemisphere gets the most solar energy during
Fall
Winter
Spring
Summer

41. And another question…..
Which statement would describe the pattern of seasons if Earth did not tilt on its axis?
Seasons would be the same because of Earth’s revolution
The seasons would be much shorter than they are now
It would be either summer or winter all year
There would be no seasons without the Earth’s tilt