Reflection, Absorption, and Albedo — Reading Comprehension

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MS-ESS2-6

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This middle school science passage, aligned with NGSS standard MS-ESS2-6, explores the interactions of incoming solar energy with Earth's surface through the processes of reflection and absorption. Students will learn the meaning of albedo, discover why snow, ice, clouds, oceans, and forests reflect or absorb sunlight differently, and examine how these differences influence Earth's energy balance and climate. The passage uses clear examples and introduces students to the critical concept of the ice-albedo feedback, which plays a role in climate change. With vocabulary support, differentiated readings, Spanish translations, and audio integration, this resource is designed to be accessible and engaging for grades 6-8. Included activities reinforce comprehension and analytical skills, making it an ideal addition to any Earth science curriculum.

CONTENT PREVIEW

Greenland Albedo Change — The map shows the difference between the amount of sunlight Greenland reflected in the summer of 2011 versus the average percent it reflected between 2000 to 2006. Virtually the entire ice sheet shows some change, with some areas reflecting close to 20 percent less light than a decade ago. Scanning electron microscope photos courtesy the Electron and Confocal Microscopy Laboratory, USDA Agricultural Research Service. / Wikimedia Commons (Public domain).

When sunlight reaches Earth, it does not behave the same everywhere. Some of the Sun’s energy bounces off surfaces, while the rest is taken in and used to warm the planet. These two processes, called reflection and absorption, are crucial for understanding Earth’s energy balance. The amount of sunlight that a surface reflects is measured by its albedo. Albedo is a fraction between 0 and 1, where higher values mean more reflection.

How Surfaces Reflect and Absorb Sunlight

Different surfaces on Earth have different albedos. For example, fresh snow and thick clouds have a high albedo, reflecting more than 80% of incoming sunlight. These bright surfaces act like giant mirrors, sending solar energy back into space. In contrast, dark surfaces like oceans and dense forests have a low albedo, reflecting less than 20%. Most of the sunlight hitting these surfaces is absorbed, turning into heat. This is why dark asphalt on a summer day gets hotter than white concrete. On average, about 30% of the Sun’s energy is reflected by Earth’s surface and atmosphere, while 70% is absorbed.

Albedo’s Role in Earth’s Climate

Albedo is not just a property of surfaces—it has a major impact on Earth’s climate system. For example, the polar regions are covered in ice and snow, giving them a high albedo. When ice melts due to warming, it exposes darker ocean water underneath. This lowers the albedo, so less sunlight is reflected and more is absorbed. The increased absorption causes more warming, which melts even more ice. This process is known as the ice-albedo feedback and is an important factor in climate change.

Interactions and Implications

Clouds also have a strong effect on albedo. Thick, low clouds reflect a lot of sunlight, helping to cool the planet. However, clouds can also trap heat, acting as insulation. Scientists use satellites to measure albedo around the world and track changes over time. Understanding albedo helps us predict weather, design energy-efficient buildings, and address environmental challenges. For example, cities can paint roofs white to reflect more sunlight and reduce cooling costs. Even small changes in albedo can have large effects on global temperatures.

In summary, the way sunlight is reflected or absorbed by Earth’s surfaces and atmosphere is a complex system with wide-ranging impacts. By studying albedo and related processes, scientists can better understand and respond to changes in our planet’s climate.

Interesting Fact:
Scientists estimate that if all Arctic sea ice melted, Earth’s average temperature could rise by more than 0.5°C due to the loss of high-albedo surfaces.

What is the definition of albedo?

The fraction of sunlight reflected by a surfaceThe amount of heat absorbed by a surfaceThe process of energy transfer by airThe speed of light in the atmosphere

Which surface has the highest albedo?

Fresh snowOcean waterDense forestAsphalt road

What percentage of incoming solar energy is absorbed by Earth on average?

10%30%50%70%

What happens during the ice-albedo feedback?

Melting ice lowers albedo, more sunlight is absorbed, and more ice meltsMelting ice increases albedo, less sunlight is absorbedSnow increases reflection, leading to coolingOceans freeze, increasing Earth's albedo

What is one way cities can use albedo to reduce cooling costs?

Paint roofs whiteBuild more roadsPlant dark-colored treesIncrease car traffic

What does the term 'energy balance' mean as used in the passage?

The balance between sunlight Earth gets and what it reflects or releasesThe amount of energy in the oceanThe difference between day and nightThe balance of wind and rain

Which is a true statement based on the passage?

Clouds can both reflect sunlight and trap heatAll surfaces on Earth have the same albedoForests reflect more sunlight than snowThe albedo of the ocean is higher than snow

Which statement best describes how satellites are used in studying albedo?

Satellites measure albedo from space to track changes on EarthSatellites increase Earth's albedoSatellites make clouds brighterSatellites melt Arctic ice

True or False: If all Arctic sea ice melted, Earth's average temperature would likely decrease.

TrueFalse

True or False: Albedo is only important in cold climates.

TrueFalse