Learning Objectives

• List the five layers of Earth's atmosphere in order from the ground up.

• Describe the key characteristics of each atmospheric layer, like temperature and unique phenomena.

• Explain the atmosphere's composition and the significance of the ozone layer.

• Identify the layers where weather, meteors, and satellites are found.

Key Vocabulary

Atmosphere

The envelope of gases that surrounds the Earth, held in place by the pull of gravity.

Troposphere

The lowest atmospheric layer where we live and all of Earth's weather takes place.

Stratosphere

This layer contains the ozone layer, which protects us from the sun's harmful ultraviolet radiation.

Mesosphere

This is the middle layer of the atmosphere where meteors burn up upon entering from space.

Thermosphere

The second-highest layer, known for its high temperatures and the location of the Aurora Borealis.

Exosphere

This is the outermost layer of our atmosphere, where it gradually thins and merges into space.

What is the Atmosphere?

• Earth has a protective layer of gases which is called the atmosphere.

• ​This layer gives us air to breathe and regulates the Earth's temperature.

• It is mainly composed of 78% nitrogen and 21% oxygen.

• The other 1% are gases like argon and carbon dioxide.

The Troposphere

• This is the lowest layer of the atmosphere, where we live.

• It extends from the surface up to about 16 km (10 miles).

• It contains 99% of water vapor, creating all weather and clouds.

• As you go higher, the temperature and air pressure become lower.

The Stratosphere

• The stratosphere is located above the troposphere, from about 16 to 50 km.

• ​This layer contains the vital ozone layer, which protects life on Earth.

• It absorbs most of the Sun's harmful ultraviolet (UV) radiation.

• Temperature increases with altitude, and airplanes fly here to avoid weather turbulence.

The Mesosphere: The Middle Layer

• The mesosphere is the middle layer, extending to about 90 km high.

• It is the coldest layer with very thin air, lacking breathable oxygen.

• It protects Earth by burning up most meteoroids entering this layer.

• These burning meteoroids are visible from Earth as “shooting stars.”

The Thermosphere and Exosphere

Thermosphere

• This layer is located from about 90 km to 600 km and is the hottest layer.

• Temperatures can reach up to 2,000°F, and its name comes from 'thermos,' meaning heat.

• The thermosphere is very hot, but its sparse gas particles transfer little heat to objects like satellites.

• The Aurora Borealis occurs here, and space shuttles fly within this atmospheric layer.

Exosphere

• The exosphere is the outermost layer of Earth's atmosphere, starting around 500–600 km and gradually merging with outer space.

  It consists mainly of hydrogen and helium, with extremely low particle density.

  Satellites orbit near the lower exosphere, while gravity is very weak at this height.

Common Misconceptions about the Atmosphere

Summary

• The atmosphere is a multi-layered gas envelope, primarily nitrogen and oxygen.

• The troposphere is where we live and where all weather occurs.

• The stratosphere has the ozone layer; the mesosphere burns up most meteors.

• The thermosphere contains auroras, and satellites orbit in the exosphere.