1. 10/5/2016
Wednesday

2. Science Log 8 Wednesday, Oct. 5:
Explain how the concept of solar angle and beam spreading are related to each other.

3. 9. Beam spreading Energy travels from the Sun to Earth as radiation.
Radiant energy travels in rays.
The number of rays hitting a given area is the energy concentration.
When lots of rays hit an area, energy concentration is high.
When few rays hit an area, energy concentration is low.

4. 9. Beam spreading
The flashlight puts out a steady beam of light rays that is about 5 cm across.
When the light beam falls on a surface from directly above (90o ), the area it covers is a circle about 20 cm2.

5. 9. Beam Spreading
When the angle that the light is coming from changes from 90o to 15o, what happens to the size of the area the beam falls on?

6. 9. Beam Spreading
When the angle that the light is coming from changes from 90o to 15o, what happens to the size of the area the beam falls on?
The area is oval, not round; the beam falls on a larger surface area; it’s about three times as large, about 60cm2.

7. 9. Beam Spreading
When the angle that the light is coming from changes from 90o to 15o, what happens to the size of the area the beam falls on?
The area is oval, not round; the beam falls on a larger surface area; it’s about three times as large, about 60cm2.
Does the amount of light in the flashlight beam change?

8. 9. Beam Spreading
When the angle that the light is coming from changes from 90o to 15o, what happens to the size of the area the beam falls on?
The area is oval, not round; the beam falls on a larger surface area; it’s about three times as large, about 60cm2.
Does the amount of light in the flashlight beam change? No

9. 9. Beam Spreading Solar Angle
The angle at which light strikes a surface is called a solar angle.
The low solar-angle rays are hitting Earth’s surface at about 15o
The light rays shining from directly overhead have a high solar angle.
They are hitting Earth’s surface at 90o
The incoming rays of light are equally spaced in both beams, but because of the difference in the angle of the Sun, three times as many rays are falling on a particular patch of Earth when the light comes from a high solar angle.
The concentration of energy is greatest when light shines on a surface at a 90o angle.

10. 9. Beam Spreading
The way a light beam covers a larger area when it hits a surface at an angle is called beam spreading.
When you take a spoonful of jam and put it on a piece of bread, it’s all concentrated in one area.
If you took a bite of that area, you’d get a lot of jam!
When you spread the jam around evenly, it is still the same total amount of jam.
If you took one bite of the bread, the jam would be a lot less concentrated.

11. 10. Vocab Put on Page 31, define in your own words, put in index
Solar angle:
Beam Spreading:

12. 11. Penny question
Answer the questions 4-6 on notebook sheet 8, Beam Spreading

13. 11. Penny question
The solar angle determines the energy concentration---the amount of energy per unit of surface area.
Since the surface area of a penny does not change, the amount of energy hitting it varies with the solar angle.
The greater the solar angle, the more energy the penny will receive.
This means that the penny would get hottest with a heat lamp at a high solar angle.
For the same reason, high solar angles result in more surface heating by the sunlight on the surface of Earth.

14. 12. Beam spreading on a globe
This is a model of Earth.
Sunlight travels about 150 million kilometers to reach Earth.
Since the Sun is so far away, the beams that hit Earth are in straight lines and equally concentrated.
We can look at how light spreads when it hits Earth’s surface by masking all the light except for one column of rays.
We’ll put a barrier with a hole between Earth and the Sun.

15. 12. Beam spreading on a globe TEACHER
Have Describe the shapes of the light beams.
Can we move the cardboard around to observe the beam-spreading effect as the beam is directed high on the globe (far north) and to the sides of the globe (morning and evening).
Can we outline a few circles

16. 13. Discuss the globe demonstration
When the beam of light hits the globe near the center of the equator, what shape is the light?
When the beam of light hits the right or left side of the globe near the equator, what shape is the light?
When the beam of light hits the globe a little bit north or south of the equator, what shape is the spot of light?
When the beam of light hits the globe near the poles, what shape is the spot of light?

17. 13. Discuss the globe demonstration
When the beam of light hits the globe near the center of the equator, what shape is the light?
Round
When the beam of light hits the right or left side of the globe near the equator, what shape is the light?
When the beam of light hits the globe a little bit north or south of the equator, what shape is the spot of light?
When the beam of light hits the globe near the poles, what shape is the spot of light?

18. 13. Discuss the globe demonstration
When the beam of light hits the globe near the center of the equator, what shape is the light?
When the beam of light hits the right or left side of the globe near the equator, what shape is the light?
A long oval
When the beam of light hits the globe a little bit north or south of the equator, what shape is the spot of light?
When the beam of light hits the globe near the poles, what shape is the spot of light?

19. 13. Discuss the globe demonstration
When the beam of light hits the globe near the center of the equator, what shape is the light?
When the beam of light hits the right or left side of the globe near the equator, what shape is the light?
When the beam of light hits the globe a little bit north or south of the equator, what shape is the spot of light?
When the beam of light hits the globe near the poles, what shape is the spot of light?

20. 13. Discuss the globe demonstration
When the beam of light hits the globe near the center of the equator, what shape is the light?
When the beam of light hits the right or left side of the globe near the equator, what shape is the light?
When the beam of light hits the globe a little bit north or south of the equator, what shape is the spot of light?
Slightly oval
When the beam of light hits the globe near the poles, what shape is the spot of light?

21. 13. Discuss the globe demonstration
When the beam of light hits the globe near the center of the equator, what shape is the light?
When the beam of light hits the right or left side of the globe near the equator, what shape is the light?
When the beam of light hits the globe a little bit north or south of the equator, what shape is the spot of light?
When the beam of light hits the globe near the poles, what shape is the spot of light?

22. 13. Discuss the globe demonstration
When the beam of light hits the globe near the center of the equator, what shape is the light?
When the beam of light hits the right or left side of the globe near the equator, what shape is the light?
When the beam of light hits the globe a little bit north or south of the equator, what shape is the spot of light?
When the beam of light hits the globe near the poles, what shape is the spot of light?
A long oval

23. 13. Discuss the globe demonstration
What time of day is the solar energy most concentrated?
What time of day is the solar energy least concentrated?
What regions of the planet are subjected to the most concentrated and least concentrated solar radiation?

24. 13. Discuss the globe demonstration
What time of day is the solar energy most concentrated?
Noon, when the Sun is at a high (large solar angle)
What time of day is the solar energy least concentrated?
What regions of the planet are subjected to the most concentrated and least concentrated solar radiation?

25. 13. Discuss the globe demonstration
What time of day is the solar energy most concentrated?
What time of day is the solar energy least concentrated?
What regions of the planet are subjected to the most concentrated and least concentrated solar radiation?

26. 13. Discuss the globe demonstration
What time of day is the solar energy most concentrated?
What time of day is the solar energy least concentrated?
Sunrise and sunset, when the solar angle is low and the energy spreads over a large area.
What regions of the planet are subjected to the most concentrated and least concentrated solar radiation?

27. 13. Discuss the globe demonstration
What time of day is the solar energy most concentrated?
What time of day is the solar energy least concentrated?
What regions of the planet are subjected to the most concentrated and least concentrated solar radiation?

28. 13. Discuss the globe demonstration
What time of day is the solar energy most concentrated?
What time of day is the solar energy least concentrated?
What regions of the planet are subjected to the most concentrated and least concentrated solar radiation?
Most concentrated in the tropics near the equator;
least concentrated in the north and south polar regions.

29. 14. Solar angle Teacher master C, solar Angle on Earth
Since Earth is round, the angle at which light hits Earth is different from place to place.
Light does not come to Earth from different angles; light strikes surfaces that are at different angles.
Remember, the angle between the incoming rays of light and the surface of the land is the solar angle.
We can see this if we think of Earth’s surface as made of lots of little, flat areas.
In this illustration, we see four rays of light coming to Earth. Ray 1 happens to strike Earth exactly perpendicular to the surface. The solar angle is 90 degrees.
Light ray 2, however, does not strike perpendicular to the surface because the surface is farther north. The solar angle, when compared to Earth’s surface, is about 60O . Light rays 3 and 4 strike the surface at even smaller angles, perhaps 45o and 30o.

30. 14. Solar angle Teacher master D, Sunlight on Earth’s Surface.
Light energy from the sun is distributed over a larger area when it hits Earth’s surface at an angle.
The beam spreads more and more the farther north or south you go.
Beam spreading does the same thing as you move east and west.
In the morning and evening, the solar angle is low, so the beam spreading is large.
In the middle of the day, the Sun’s energy is most concentrated because the sun is overhead at a high solar angle.

31. 15. Focus Question 3
The greater the solar angle, the greater the concentration of radiant energy.
Light shining from directly above is most intense; light coming at an angle is less concentrated.
Almost all the energy coming to Earth is solar energy. Light absorbed by the land, water, and air is converted to heat.

32. Why is it hotter in the summer? Be ready to share
15. Focus Question 3
Discuss in your groups
Why is it hotter in the summer?
Be ready to share

33. 15. Focus Question 3
Areas where the Sun shines directly down on Earth receive more intense energy than areas that experience beam spreading.

34. 15. Focus Question 3
Areas where the Sun shines directly down on Earth receive more intense energy than areas that experience beam spreading.
The greater the amount of energy absorbed, the hotter the area becomes.

35. 15. Focus Question 3
Areas where the Sun shines directly down on Earth receive more intense energy than areas that experience beam spreading.
The greater the amount of energy absorbed, the hotter the area becomes.
Since Earths axis is tilted 23.5o and the Northern Hemisphere leans toward the Sun in the summer, our town receives more intense solar energy in the summer months.

36. 15. Focus Question 3 Why is it hotter in the summer?
Go back to your focus question
Why is it hotter in the summer?
On your own, record your final answer to your focus question.

37. 16. Response sheet
Work individually to respond to the items on response sheet investigation 3, notebook sheet 9
Put it on page 32
Write responses on page 33 in your notebook, save room to add information.

38. Vocabulary section 3
Update vocab page 31, if needed add drawings or details, make sure you put them in your index.
Beam spreading: the way a light beam covers a larger area when it hits a surface at an angle.
Season: a period of the year identified by changes in hours of daylight and weather
Solar angle: the angle at which light passes through the atmosphere; measured from Earth’s surface