Activity 1A-Flashlights on Earth
Unit 1- Energy
Background Information for the Teacher
Activity
In this hands-on activity,
learners create a model to
show how the angle of the
Sun’s incoming rays, due
to the shape and tilt of the
Earth, affect the amount
of energy reaching the
Earth’s surface. Students
explore the relationship
between solar intensity
and the incoming angle of
the sunlight, also known as
the angle of incidence.
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NSES 5-8
Science as Inquiry Std A:
Mathematics is important
in all aspects of scientific
inquiry.
Physical Science Std B:
Energy is transferred in
many ways.
Heat moves in predictable
ways, flowing from warmer
objects to cooler ones,
until both reach the same
temperature.
Light interacts with matter
by transmission (including
refraction), absorption,
or scattering (including
reflection).
The sun is a major source
of energy for changes on
the earth's surface. The sun
loses energy by emitting
light. A tiny fraction of that
light reaches the earth,
transferring energy from
the sun to the earth. The
sun's energy arrives as light
with a range of wavelengths,
consisting of visible light,
infrared, and ultraviolet
radiation.
Earth Science Std D:
The sun is the major source
of energy for phenomena
on the earth's surface, such
as growth of plants, winds,
ocean currents, and the
water cycle. Seasons result
from variations in the amount
of the sun's energy hitting
the surface, due to the tilt of
the earth's rotation on its axis
and the length of the day.
CLEP
Principle 1: The sun is the
primary source of energy
for Earth's climate system.
1C: The tilt of Earth’s
axis relative to its orbit
around the Sun results in
predictable changes in the
duration of daylight and
the amount of sunlight
received at any latitude
throughout a year. These
changes cause the annual
cycle of seasons and
associated temperature
changes.
ELF
Energy 1: Solar energy is
the driving force for Earth’s
climate system.
Energy 1a: Solar energy
measured at the Earth’s
surface (insolation) varies
due to Earth’s shape, its
orientation with respect
to the Sun, and the
characteristics of its orbit
around the Sun. Earth’s
tilt and orbit cause the
annual cycle of seasons
and associated temperature
changes. Cyclical, long-term
changes in Earth’s orbit
and tilt, called Milankovitch
Cycles, have profound
effects on insolation and
therefore global climate.
Activity 1A-Flashlights on Earth
Unit 1- Energy
NSES: National Science Education Standards (http://www.csun.edu/science/ref/curriculum/reforms/nses/index.html)
CLEP: Climate Literacy Essential Principles (http://www.climatescience.gov/Library/Literacy/)
ELF: Environmental Literacy Framework (www.andrill.org/education/elf)
Additional Information:
Climate and Earth’s Energy Budget
http://earthobservatory.nasa.gov/Features/EnergyBalance/page1.php
Background Information
One could say that we live on a ‘solar-powered’ planet. The solar radiation that reaches Earth’s surface is the energy that
drives many of the processes acting on the surface of the Earth, including our weather and climate, wind and ocean
currents, and life-giving photosynthesis. The Sun’s energy travels to Earth in the form of electromagnetic radiation. Solar
energy travels 93 million miles (150 million kilometers) through space, from the Sun to Earth. Because of the distance
that it travels, solar radiation contacts the Earth's surface in essentially parallel lines.
Solar radiation that makes it to Earth’s atmosphere and surface is called solar insolation (this is short for incoming solar
radiation). Satellite measurements have shown that on average, 342 watts per square meter of solar radiation reaches
the top of Earth’s atmosphere. About 70% of that energy (in the form of visible and infrared light) makes it through the
atmosphere and enters the Earth’s climate system. We sense this incoming solar radiation in the form of heat and light.
Because the angle of incoming sunlight is lower at higher latitudes, and it must travel through a greater amount of
atmosphere, more energy is absorbed by the atmosphere. For these two reasons, less solar radiation is available to be
absorbed by any given area in the Polar Regions, making them colder. However, thanks to the air and ocean currents,
absorbed heat energy near the Equator is transported (via convection, conduction, and evaporation) to the Polar Regions.
This transfer of energy from warmer to cooler regions of the Earth is important because it helps to stabilize and equalize
the climate of the planet.
Presently, the Earth’s axis is tilted at an angle of 23.5˚ to the plane of its revolution around the Sun. Therefore, over the
course of a year, as Earth revolves around the Sun, its inclination angle towards the Sun also changes. This change
causes a variation in the light (and heat) intensity that occurs on Earth’s surface.
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Activity 1A-Flashlights on Earth
Additional Resources:
Image source: http://scijinks.nasa.gov/weather-v-climate
Image source: http://scijinks.jpl.nasa.gov
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Unit 1- Energy