Seasons and Sun. Sun Angle and Solar Heating Investigation 3, Part 3. Lesson Objective: I can explain how beam spreading affects the temperature of the Earth in different locations. The tilt of Earth’s axis produces changes in day length over the course of a year. Review.
Sun Angle and Solar Heating
Investigation 3, Part 3
The tilt of Earth’s axis produces changes in day length over the course of a yearReview
Earth rotates on its axis to produce day and night
more time for the Sun’s energy to be absorbed by the:
But could there be more to this story?
Circle the brightest spot on the graph paper over the course of a yearLight Model
Observe the spot of light where the beam hits the floor
To represent a beam of light from the Sun
Form of energy over the course of a year
The circles show the area that the energy beam covered at two different times.
Both are sources of light energy.
Spot gets bigger as the angle between the beam of light and floor gets smaller.
Energy travels from the Sun to Earth as radiation, or solar energy. Heat is transferred to the Earth by radiation.
Angle at which light strikes a surface (add definition to ISN)
Light rays from directly overhead have a high solar angle.
Low solar angle rays hit the Earth’s surface at about 15˚.
When fewer rays hit an area, the energy density is low. Not as much energy is transferred to that part of the Earth.Energy Density-
Number of rays hitting a given area is the energy density. (add definition to ISN and draw a picture of this example)
When lots of rays hit an area, the energy density is high.
Notice rays are equally spaced in both beams,
but because of solar angle,
there are three times as many rays when it is from a high solar angle.
Amount of energy hitting it varies with the solar angle
Surface area of a penny does not change
The greater the angle, the greater the energy it will receive.
Earth is round = the angle at which light hits it is different from place to place
Earth viewed as many flat surfaces
Light strikes surfaces that are at different angles.
Angle between the incoming rays of light and the surface of the land is the solar angle.
Solar angle = 60˚
Solar angle = 90˚
Light energy from the Sun is distributed over a larger area when it hits Earth’s surface at an angle.
Beam spreads more and more the farther north or south your go.
Does the same thing if you move east and west
Energy is most intense
High solar angleBeam spreading is small, the angle is 90 degrees at noon, so that is the most intense time of day
Energy is least intense
Low solar angleBeam spreading is large
Solar energy is most intense during the middle of the day in the tropics.
Energy is least intense in the morning, evening and extreme north and south regions.