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What is the Hottest Layer of the Atmosphere — Reading Comprehension

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This reading passage delves into the thermosphere, the hottest layer of Earth's atmosphere, and its fascinating characteristics. It is designed for middle school students (grades 6-8) and aligns with the NGSS standards related to Earth's systems. The passage explains why the thermosphere reaches extreme temperatures, the role of the ionosphere in radio communication, and the cause of the aurora. It also connects the thermosphere to real-world applications like the orbit of the International Space Station. The content uses clear, factual language, bolding key terms, and is structured to aid comprehension for self-study. The passage includes engaging examples and a fun fact to reinforce key concepts, making it a valuable educational resource for students studying atmospheric science.

CONTENT PREVIEW

Hottest-Layer-Atmosphere — The thermosphere, Earth's hottest atmospheric layer, and the location of the International Space Station's orbit.

The Earth's atmosphere is a protective blanket of gases, divided into several distinct layers. While you might think the layers closest to the ground are the warmest, the highest layer, the thermosphere, is actually the hottest. This is because the thermosphere absorbs high-energy solar radiation, such as X-rays and ultraviolet (UV) light, which causes the temperature to soar. Although the temperature can reach thousands of degrees Celsius, a thermometer would feel extremely cold here. The reason is the air density. There are so few gas molecules, spaced so far apart, that they do not transfer much heat to an object, such as a thermometer.

The thermosphere is located above the mesosphere and extends from about 90 km to between 500 and 1,000 km above Earth's surface. Within this layer is the ionosphere, a region of the atmosphere that is full of charged particles, or ions. The ions are created when the Sun’s high-energy radiation strips electrons from gas molecules. The ionosphere is crucial for our lives on Earth. It is the region where radio waves are reflected, allowing for long-distance radio communication. Without the ionosphere, radio signals would simply travel out into space.

A well-known phenomenon that occurs in the thermosphere is the aurora. These spectacular light shows, also known as the Northern and Southern Lights, are created when charged particles from the Sun collide with atoms and molecules in the thermosphere. These collisions excite the atmospheric gases, causing them to emit light. This process is similar to how a neon sign works. The specific color of the aurora depends on the type of gas molecule being hit and the altitude. For example, collisions with oxygen often produce a greenish glow, while nitrogen can create a red or purple hue.

The thermosphere is also where the International Space Station (ISS) orbits Earth. The extremely low density of the air at this altitude means there is very little drag, allowing the ISS to maintain its speed and orbit for extended periods. The low air density is also why we don't feel the extreme heat of the thermosphere on Earth.

Fun Fact: The thermosphere is where meteors and space debris burn up. The friction with the sparse air molecules, even though they are few, is enough to cause the object to heat up and glow brightly as it enters this layer.

Which of the following is the primary reason the thermosphere is the hottest layer of the atmosphere?

It is the closest layer to the Sun.It absorbs high-energy solar radiation.It has the highest concentration of greenhouse gases.It contains the most dense air molecules.

The ionosphere is an important part of the thermosphere because it is responsible for what?

Protecting us from meteors.Generating the Earth's magnetic field.Reflecting radio waves for communication.Creating weather patterns.

Based on the passage, why would a thermometer register a very cold temperature in the thermosphere despite the high temperatures?

The thermometer is not designed for that altitude.The gas molecules are spaced too far apart.The Sun's energy is not strong enough to heat the thermometer.The Earth's core is too far away to provide heat.

Which phenomenon is directly caused by charged particles from the Sun colliding with atmospheric gases in the thermosphere?

Solar eclipsesThe auroraThunderstormsThe formation of clouds

A scientist is studying a new type of radio communication that requires signals to bounce off a specific atmospheric layer to travel long distances. Which layer would the scientist most likely be focusing on?

MesosphereTroposphereStratosphereThermosphere

What is the main idea of the passage?

The thermosphere is the most important layer of the atmosphere for living things.The thermosphere is the hottest layer of the atmosphere due to solar radiation and is home to unique phenomena like the aurora.The different layers of the atmosphere are defined by their temperature.The International Space Station orbits in the thermosphere to avoid the heat.

What is the primary role of the thermosphere in absorbing radiation?

It absorbs harmful X-rays and UV light from the sun.It traps greenhouse gases, warming the planet.It absorbs cosmic rays from deep space.It reflects visible light, causing the sky to appear blue.

What makes the aurora so colorful?

The different types of gas molecules that are hit by solar particles.The varying speeds of the solar particles.The reflection of sunlight off of water vapor.The way the Earth's magnetic field bends the light.