The Atmosphere

The Atmosphere

Substitute Teacher Lesson

​Living Earth Biology

​Atmospheric Properties

​The thin envelope of air that surrounds our planet is a mixture of gases, each with its own physical properties. The mixture is far from evenly divided. Two elements, nitrogen and oxygen, make up 99% of the volume of air. The other 1% is composed of “trace” gases, the most prevalent of which is the inert gaseous element argon.

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The rest of the trace gases, although present in only minute amounts, are very important to life on earth. Two in particular, carbon dioxide and ozone, can have a large impact on atmospheric processes.

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Another gas, water vapor, also exists in small amounts. It varies in concentration from being almost non-existent over desert regions to about 4% over the oceans. Water vapor is important to weather production since it exits in gaseous, liquid, and solid phases and absorbs radiant energy from the earth.

Open Ended

In your own words, what is the atmosphere?

Multiple Choice

What two gasses make up around 99% of the atmosphere?

• Carbon dioxide and water vapor

• Oxygen and carbon dioxide

• Nitrogen and oxygen

• Oxygen and water vapor

Multiple Choice

Which three trace gasses are very important to Earth?

• Oxygen, Argon, Carbon dioxide

• Carbon dioxide, Water vapor, Ozone

• Ozone, Nitrogen, Water Vapor

• Carbon dioxide, Water vapor, Argon

Multiple Choice

The layer structure of the earth's atmosphere is based on:

• Altitude/thickness

• chemical makeup

• color/shade

• temperature

Multiple Choice

Which layer or sphere of the earth's atmosphere includes the ozone layer?

• Thermosphere

• Stratosphere

• Troposphere

• Mesosphere

Open Ended

Describe the thickness of the atmosphere relative to the diameter of the Earth

Open Ended

In order, beginning from the earth's surface, what are the four layers or "spheres" of the earth's atmosphere?

Multiple Choice

The atmosphere protects the earth by filtering out  what?

• Sunlight

• Harmful chemicals

• Dust

• Smoke

Multiple Choice

What percentage of a sunbeam actually reaches the earth's surface without being scattered, absorbed or reflected?

• 17%

• 27%

• 37%

• 7%

Earth's atmosphere has a series of layers, each with its own specific traits. Moving upward from ground level, these layers are called the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The exosphere gradually fades away into the realm of interplanetary space.

Open Ended

What do you think holds the atmosphere to the planet?

Troposphere

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The troposphere is the lowest layer of our atmosphere. Starting at ground level, it extends upward to about 10 km (6.2 miles or about 33,000 feet) above sea level.

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We humans live in the troposphere, and nearly all weather occurs in this lowest layer. Most clouds appear here, mainly because 99% of the water vapor in the atmosphere is found in the troposphere.

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Air pressure drops, and temperatures get colder, as you climb higher in the troposphere.

Stratosphere

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The next layer up is called the stratosphere. The stratosphere extends from the top of the troposphere to about 50 km (31 miles) above the ground.

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The infamous ozone layer is found within the stratosphere. Ozone molecules in this layer absorb high-energy ultraviolet (UV) light from the Sun, converting the UV energy into heat.

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​OZONE

​In the atmosphere, ozone and oxygen block almost all of the shortest wavelength radiation.

• UV-C is absorbed and does not reach he surface.

• UV-B radiation is blocked efficiently but not completely.

• UV-A is only partially absorbed by ozone; most penetrates to the surface

Open Ended

We wear sunscreen to prevent damage from UV radiation. What do you think would happen to us if there were no Ozone Layer?

Unlike the troposphere, the stratosphere actually gets warmer the higher you go! That trend of rising temperatures with altitude means that air in the stratosphere lacks the turbulence and updrafts of the troposphere beneath.

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Commercial passenger jets fly in the lower stratosphere, partly because this less-turbulent layer provides a smoother ride. The jet stream flows near the border between the troposphere and the stratosphere

Mesosphere

Above the stratosphere is the mesosphere. It extends upward to a height of about 85 km (53 miles) above our planet. Most meteors burn up in the mesosphere.

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Unlike the stratosphere, temperatures once again grow colder as you rise up through the mesosphere. The coldest temperatures in Earth's atmosphere, about -90° C (-130° F), are found near the top of this layer. The air in the mesosphere is far too thin to breathe (the air pressure at the bottom of the layer is well below 1% of the pressure at sea level and continues dropping as you go higher).

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Multiple Choice

The mesosphere helps protect Earth from what threat?

• UV Radiation

• Airplanes

• Meteors

• Aliens

Thermosphere

The layer of very rare air above the mesosphere is called the thermosphere. High-energy X-rays and UV radiation from the Sun are absorbed in the thermosphere, raising its temperature to hundreds or at times thousands of degrees.

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However, the air in this layer is so thin that it would feel freezing cold to us! In many ways, the thermosphere is more like outer space than a part of the atmosphere. Many satellites actually orbit Earth within the thermosphere!

Variations in the amount of energy coming from the Sun exert a powerful influence on both the height of the top of this layer and the temperature within it. Because of this, the top of the thermosphere can be found anywhere between 500 and 1,000 km (311 to 621 miles) above the ground.

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Temperatures in the upper thermosphere can range from about 500° C (932° F) to 2,000° C (3,632° F) or higher. The aurora, the Northern Lights and Southern Lights, occur in the thermosphere

Multiple Choice

What two things are sometimes found in the Thermosphere?

• Satellites and Auroras

• Jet planes and Satellites

• Auroras and Clouds

• Clouds and Escaped balloons

Exosphere

Although some experts consider the thermosphere to be the uppermost layer of our atmosphere, others consider the exosphere to be the actual "final frontier" of Earth's gaseous envelope. As you might imagine, the "air" in the exosphere is very, very, very thin, making this layer even more space-like than the thermosphere. In fact, the air in the exosphere is constantly - though very gradually - "leaking" out of Earth's atmosphere into outer space.

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There is no clear-cut upper boundary where the exosphere finally fades away into space. Different definitions place the top of the exosphere somewhere between 100,000 km (62,000 miles) and 190,000 km (120,000 miles) above the surface of Earth. The latter value is about halfway to the Moon!

Open Ended

The air gets thinner in the atmosphere as you gain altitude. In other words, you find less and less gas molecules the further you get from the surface of the Earth. How might you explain this?

Draw

Use a different color and draw a line from the term in the word box to the correct layer.