Performance Benchmark E.12.A.1
Students know the Sun is the major source of Earth’s energy, and provides the energy
driving Earth’s weather and climate. E/S
More than 99% of the Earth’s energy comes from the Sun. This energy is transferred to
Earth mostly through visible light. The Earth also sends energy back into outer space,
mostly as infrared radiation. On average, this transfer of this incoming and outgoing
energy is nearly equal. Scientist therefore state that the Earth is in radiative equilibrium
with the Sun.
Of the Sun’s incoming energy, about 30% is reflected back to space. Another 19% of the
incoming solar energy is absorbed by the Earth’s atmosphere and clouds. The remaining
51% is absorbed by the Earth’s surface. Most of the energy that reaches the Earth’s
surface is in the form of visible light.
Figure 1: The global energy balance between the Earth’s surface and atmosphere (from
http://rst.gsfc.nasa.gov/Sect14/Sect14_1a.html)
To maintain equilibrium, the Earth returns the energy it receives from the Sun back to
space as infrared light. However, only 6% of the energy goes directly from the Earth’s
surface to space. About 15% of the Earth’s surface energy is absorbed by water vapor,
carbon dioxide and other gases in the atmosphere. This is called the greenhouse effect
and is a common condition on planets with relatively thick atmospheres.
To learn more about the greenhouse effect go to
http://epa.gov/globalwarming/kids/greenhouse.html
The remainder of Earth’s surface energy is transferred to the atmosphere in a more
complex exchange involving sensible and latent heat.
Sensible heat is the energy associated with the temperature of a body. A warm surface
will be at a higher temperature. Sensible heat flows from the surface to the atmosphere
via convection (air circulations) or conduction (molecular motion).
Latent heat is the energy associated with phase changes. In the atmosphere, water vapor
condenses forming clouds and precipitation. This releases latent heat to the atmosphere.
Latent heat also flows from the atmosphere to the surface during evaporation.
Evaporation cools the atmosphere.
To learn more about sensible and latent heat flux go to
http://www.physicalgeography.net/fundamentals/7j.html
So, infrared radiative transfer combined with flux of sensible and latent heat provides the
energy to the atmosphere. This energy, which ultimately originated from the Sun, drives
all of Earth’s weather and climate.
Performance Benchmark E.12.A.1
Students know the Sun is the major source of Earth’s energy, and provides the energy
driving Earth’s weather and climate. E/S
Common misconceptions associate with this benchmark:
1. Students incorrectly think the Moon is the primary source of energy for weather
and climate processes.
Tide effects from the Moon have virtually no effect on the atmosphere. Although sea and
lake tides are often reported with the weather forecast, there is no appreciable relationship
between weather, climate, and tides.
Ocean currents near the shore can affect how high or low tides can rise at a shoreline. The
rising and falling of tides can cause flood and ebb currents, which may have result in
substantial movement of water in and out of bays and harbors. But, tides do not have an
effect on major ocean currents that strongly influence Earth’s global climate.
A detailed discussion of misconceptions associated with tides is found at
http://www.lhup.edu/~DSIMANEK/scenario/tides.htm
2. Students incorrectly believe that the Earth’s internal energy is the primary source
of energy for weather and climate processes.
While Earth’s internal energy is considerable, it is accounts for less than 1% of the
Earth’s energy budget (energy from the Sun accounts for more than 99%).
To learn more about the Earth’s total energy budget, see
http://www.tulane.edu/~sanelson/geol204/struct&materials.htm
The Earth’s internal energy comes from two sources. The first is the warming caused by
the formation of the planet. Scientific evidence indicates Earth and the other planets
were formed by accretion (collisions and sticking) of planetesimals. The kinetic energy of
these impacts raised the planet’s temperature as it formed, so much so, that early Earth
consisted of melted rock and metal. Since that time, Earth has been slowly cooling as
this primordial internal energy is radiated back to space. The second source of internal
energy is from decay of radioactive elements present in Earth materials. For example, the
decay of Uranium-238 in the Earth’s crust, mantle, and core release energy that
ultimately warms surrounding material.
A more detailed discussion of radioactive decay and its effect on Earth’s total energy is
found at http://fermat.nap.edu/books/ARC030765/html/23.html
The Earth’s internal energy drives plate tectonics, which can results in amazing effects
such as tearing apart continents and creating new mountain ranges. But plate tectonics
work slowly (i.e., on a geologic time scale), with average movement of only a few
centimeters per year. Energy from the Sun drives drastic changes to Earth’s
atmosphere—called weather—causing the precipitation and wind that erodes these
mountain ranges. Additionally, the atmosphere retains enough of the Sun’s energy to
raise the Earth’s surface temperature by more than 30 degrees Celsius (60 degrees
Fahrenheit). This is called the greenhouse effect and is a common occurrence on planet’s
with relatively thick atmospheres.
More about the greenhouse effect can be found at
http://www.epa.gov/climatechange/kids/greenhouse.html
4. Students confuse the properties of force and energy.
In Star Wars Episode IV, Obi Wan Kenobi tells Luke Skywalker that “The Force is an
energy field created by all living things.” This statement typifies confusion about the
terms energy and force. An appreciable part of this confusion resides in misconceptions
about the relationship between force and motion. Many students incorrectly believe that a
moving object must have an “impetus” force causing it to stay in motion. Students
incorrectly believe that this impetus force is applied to an object by a collision with
another object (i.e., hitting a baseball with a bat) and that this “impetus force” then
resides within the object even after it has lost contact with the original impactor, causing
it to continue moving until this impetus is somehow dissipated.
To learn more about the impetus misconception, go to
http://modeling.asu.edu/R&E/forceConceptionTaxon92.doc
Before Galileo, the prevailing scientific thought upheld the belief of force impetus, where
some incorrectly believed that this force depended on the speed and mass of the object.
Note how closely the incorrect idea of force impetus relates to correct understandings
about kinetic energy. Starting with Galileo and Newton, scientists now know that an
object will remain in constant motion (either at rest or traveling in the same direction
with the same speed) unless acted upon by a net force. Therefore, force is not required for
motion, but only to change an object’s motion (direction and/or speed). Forces act upon
objects, but are not an inherent quality within the object.
A detailed discussion of Newton’s First Law of Motion is found at
http://www.physicsclassroom.com/Class/newtlaws/U2L1a.html
On the other hand, energy is an inherent quality of an object. If the object is moving, it
has kinetic energy. Also, within the object there exists internal kinetic energy associated
with molecular motions of the object’s material. The object would also have potential
energy due to position within a gravitational, electrical, magnetic, and/or other type of
force field.
An overview about the forms of energy can be read at
http://www.eia.doe.gov/kids/energyfacts/science/formsofenergy.html
Performance Benchmark E.12.A.1
Students know the Sun is the major source of Earth’s energy, and provides the energy
driving Earth’s weather and climate. E/S
Sample Test Questions
1. Earth’s surface absorbs mainly which types of energy?
a. Ultraviolet light and x-rays
b. Infrared and visible light
c. Ultraviolet and infrared light
d. Visible and ultraviolet light
2. The energy source driving Earth’s weather comes from
a. the Earth’s core through heat conduction.
b. release of radiant heat energy through volcanic activity.
c. the Sun through visible light.
d. the Moon through tides.
3. The Earth’s surface mainly gives off (radiates) which form of energy?
a. Infrared light
b. Visible light
c. Ultraviolet light
d. The Earth’s surface does not give off energy
4. About 70% of the Sun’s energy directed toward Earth is absorbed by the Earth’s
surface, clouds, and atmosphere. What happens to the rest of the energy?
a. The energy is lost as it overcomes the Sun’s gravity.
b. The energy is reflected by clouds, water, and land back into space.
c. The energy is diminished as it traveling through space.
d. The energy is reflected by the Moon back into space.
5. Weather is caused by the Sun’s energy warming the Earth’s surface unevenly.
Which of the following is NOT a contributing factor to this uneven warming?
a. Different surfaces warm at different rates.
b. Different surfaces retain energy differently.
c. The Sun is farther away during the winter.
d. The Sun’s rays strike the surface at different angles depending on latitude.
6. More of the Sun’s energy is received at the Earth’s tropical regions than in the
arctic regions because the tropical regions
a. are covered by a greater area of land.
b. have more vegetation that absorbs the Sun’s energy.
c. have a thinner atmosphere than the polar regions.
d. receive sun rays closest to vertical.
7. The following figure shows the angle of the sun’s rays hitting two different
locations on the Earth’s surface. Which of the statements about the figure is most
correct?
A
B
a. Area A shows a location near the pole and Area B shows a location near
the equator. Warming of the Earth is more with Area B than Area A
because Sun’s energy is spread over a wider area.
b. Area A shows a location near the pole and Area B shows a location near
the equator. Warming of the Earth is more with Area A than Area B
because the atmosphere is thinner at the equator.
c. Area A shows a location near the equator and Area B shows a location
near the pole. Warming of the Earth is more with Area A than Area B
because the atmosphere is thinner at the equator.
d. Area A shows a location near the equator and Area B shows a location
near the pole. Warming of the Earth is more with Area A than Area B
because the Sun’s energy is spread concentrated within a smaller area.
Performance Benchmark E.12.A.1
Students know the Sun is the major source of Earth’s energy, and provides the energy
driving Earth’s weather and climate. E/S
Answers to Sample Test Questions
1.
2.
3.
4.
5.
6.
7.
(b)
(c)
(a)
(b)
(c)
(d)
(d)
Performance Benchmark E.12.A.1
Students know the Sun is the major source of Earth’s energy, and provides the energy
driving Earth’s weather and climate. E/S
Intervention Strategies and Resources
The following list of intervention strategies and resources will facilitate student
understanding of this benchmark.
1. Introduction to the Atmosphere
The National Center for Atmospheric Research has produced “An Introduction to
the Atmosphere.” Content and lessons that relate the Sun’s energy to weather and
climate are found at http://www.ucar.edu/learn/1_1_1.htm. Specifically, Activities
5, 6, and 7 are lessons that deal with the following atmospheric energy transfer
processes: radiation, conduction, and convection. The direct links to these lessons
are:

Atmospheric Processes-Radiation
(http://www.ucar.edu/learn/1_1_2_5t.htm)

Atmospheric Processes-Conduction
(http://www.ucar.edu/learn/1_1_2_6t.htm)

Atmospheric Processes-Convection
(http://www.ucar.edu/learn/1_1_2_7t.htm)
2. Sun’s Impact on the Earth’s Climate
For those that have access to an Internet lab, this series of lessons show the Sun’s
effect on planetary temperatures and weather. These five lessons were developed
by the Physics and Astronomy Education Research Group at Montana State
University and are found at http://btc.montana.edu/CERES/html/Suns/suns1.html.
3. Sunspots and Climate
This lesson, found at
http://eo.ucar.edu/educators/ClimateDiscovery/LIA_lesson7_9.28.05.pdf, was
developed by the National Center for Atmospheric Research. In “Sunspots and
Climate” students plot periods of high and low sunspot activity and correlate these
to periods to temperature variation on Earth, which reinforces the Sun as the
driver of Earth’s climate and weather.
4. Visualization of Seasonal Sunlight on Earth
Developed from Earth images captured by a geostationary satellite, a nice
animation found at
http://www.classzone.com/books/earth_science/terc/content/visualizations/es1704
/es1704page01.cfm?chapter_no=visualization shows how sunlight varies on the
globe as the year progresses.