Cloudy vs. Clear - Maps
Students will analyze and interpret maps of the average net atmospheric radiation to compare the flow of energy from the Sun toward Earth in different months and for cloudy versus clear days. Students will draw conclusions and support them with evidence.
- Students will analyze and interpret maps showing energy from the Sun in different months
- Students will analyze and interpret maps showing energy from the Sun on clear and cloudy days
- Students will draw conclusions about differences in the amount of energy from the Sun that reaches land, water, and air on cloudy versus clear days
- How do clouds affect the amount of energy the Earth receives from the Sun?
- What are the differences in the amount of energy received in the Northern Hemisphere in different seasons?
- What are the differences in the amount of energy received in different hemispheres in the same month?
- Student worksheets
- Blank paper or notebooks to record map observations
- Data Literacy Cubes (optional)
- Map Cubes (or number cubes)
- Map Cube question sheets (Select level/s based upon student readiness.)
- Standalone Lesson (no technology required)
Prerequisites Student Knowledge
- Knowledge that the Sun's energy heats land, water and air of the Earth
- Knowledge of cardinal directions on a map
- Seasons in the Northern Hemisphere
- Introduction to the cause of Earth's seasons
Practice interpreting map images
- Group students.
- Distribute clear day map images from July to groups.
- Direct students to compare the images.
- Option 1: Have groups use the Data Literacy Cube - Map Cube to analyze the maps and write answers for at least 10 different questions.
- Option 2: Have groups analyze the maps without the Data Literacy Cube, record observations and discuss what it means.
- If students need help interpreting the images, point out the scale at the top of the maps.
- Have students note which colors are positive and negative.
- Positive numbers represent warming. The higher the number, the more warming.
- Negative numbers represent cooling. The lower the number, the more cooling.
Compare images from different months
- Review the months for the seasons in the Northern Hemisphere if necessary.
- Distribute clear day map images from January to groups.
- Have groups compare the clear day January and July images and answer the questions.
- What do you see on the July map?
- What do you see on the January map?
- What differences do you see between the two maps?
- What do you think the reason is for the differences you see?
Compare images for cloudy versus clear days
- Collect the clear day map images for January and have students keep the clear day map images for July.
- Hand out the cloudy day map images for July.
- Have groups compare the images and answer the questions.
- What do you see on the cloudy day map?
- Identify any areas in the Northern Hemisphere where there is cooling with and without clouds.
- What do you think could cause cooling during this season?
- What differences do you see between the two maps?
- What do you think is the reason for the differences?
- Where do you think the most clouds were during the month of July?
- Have students write one sentence describing the difference in the energy from the Sun in the Northern Hemisphere in January and July.
- Have students write one sentence describing the difference in the energy from the Sun on cloudy versus clear days in July.
Compare data from China to local data obtained from the Earth System Data Explorer. The date can be found under Atmosphere > All Data > Net Atmospheric Radiation. There are two datasets, one with clouds and one without. Tutorials are available here.
Teacher Background Information
The Sun's radiant energy is the fuel that drives Earth's climate engine. The Earth-atmosphere system constantly adjusts to maintain a balance between the energy that reaches the Earth from the Sun and the energy that flows from Earth back out to space. Energy received from the Sun is mostly in the visible (or shortwave) part of the electromagnetic spectrum, where Earth's atmosphere is transparent. The solar radiation absorbed by the Earth causes the planet to heat up until it is radiating (or emitting) as much energy back into space as it absorbs from the Sun. The Earth's thermal emitted radiation is mostly in the infrared (or longwave) part of the spectrum, where Earth's atmosphere is not transparent. Thus, much of the emission to space is from the higher levels of the atmosphere.
The balance between incoming and outgoing energy is called the Earth's radiation budget. The difference between the incoming and outgoing energy is called net radiation. A positive value of net radiation means that there is more incoming energy than outgoing energy, which results in the surface and atmosphere warming. The opposite is true when the net radiation is negative.
Net Radiation, Albedo, and the Urban Heat Island
Not all incoming solar radiation is absorbed. About 30% of the solar energy that comes to Earth is reflected back to space by clouds and aerosols or bright surfaces. The ratio of reflected-to-incoming energy is called "albedo" from the Latin word meaning whiteness. Different surfaces reflect the Sun's energy at different rates and thus have different albedos.
Changing surfaces can lead to changing albedo values and changes to the net radiation. For example, the melting of ice replaces a white surface with a darker surface, decreasing the albedo of the surface. This change allows for more energy to be absorbed at the surface and makes the net radiation more positive. When urbanization causes changes to Earth's surface which change the net radiation and increase temperatures in a local area, this is called an Urban Heat Island effect.
Net Radiation and the Seasons
The seasons are caused as the Earth, tilted on its axis, travels in its orbit around the Sun each year. The hemisphere that is tilted toward the Sun absorbs more energy from incoming sunlight (summer) that the hemisphere tilted away from the Sun (winter). During this lesson, students will view NASA data displaying the net radiation in one calendar year during clear and cloudy sky conditions.
Why Does NASA Study This Phenomenon?
Scientists monitor the Earth System to better understand and meet the challenges of environmental change. For example, knowing how much of the Sun's energy reaches the surface of the Earth helps scientists understand dynamics in the spheres within the Earth System, i.e., Atmosphere, Hydrosphere, Cryosphere, and Biosphere. An important variable in understanding these changes is Net Radiation because it impacts temperatures. The warm air rising off Earth's landscapes influences our world's weather and climate patterns. NASA leads a wide range of efforts, including CERES, to collect and interpret these data acquired from satellites, aircraft, and ground networks, and to integrate these data into numerical models of the Earth’s climate at global and regional scales.
CERES products include both solar-reflected and Earth-emitted radiation from the top of the atmosphere to the Earth's surface, from which the net radiation can be calculated. Cloud properties are determined using simultaneous measurements by other EOS and NPP instruments such as the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Visible Infrared Imaging Radiometer Suite (VIIRS). Analyses using CERES data build upon the foundation laid by previous missions such as the NASA Earth Radiation Budget Experiment (ERBE), leading to a better understanding of the role of clouds and the energy cycle in global climate change.
For more information on CERES see http://ceres.larc.nasa.gov.