Mesosphere

Definition

The mesosphere is the third layer of Earth's atmosphere, situated above the stratosphere and below the thermosphere, extending from about 50 km to 85 km above sea level. It plays a critical role in atmospheric dynamics and is characterized by decreasing temperatures with altitude, making it the coldest layer of the atmosphere. This layer is where most meteorites burn up upon entering Earth's atmosphere, highlighting its significance in protecting the planet from space debris.

5 Must Know Facts For Your Next Test

1. Temperatures in the mesosphere can drop as low as -90°C (-130°F), making it the coldest atmospheric layer.
2. The mesosphere extends approximately from 50 km to 85 km above Earth’s surface.
3. This layer is where most meteors are incinerated before they can reach the surface, contributing to the protection of Earth.
4. Unlike the stratosphere, which contains ozone, the mesosphere lacks significant amounts of ozone and other greenhouse gases.
5. The boundary between the mesosphere and thermosphere is known as the mesopause, which marks a transition point where temperatures begin to rise again.

Review Questions

• What are the temperature characteristics of the mesosphere and how do they compare to other atmospheric layers?
  • The mesosphere is known for having decreasing temperatures with increasing altitude, reaching its coldest point around -90°C (-130°F) at its upper boundary. This contrasts with the stratosphere below it, where temperatures are relatively stable and warmer due to the presence of ozone. Above in the thermosphere, temperatures rise significantly due to solar radiation absorption. The stark temperature differences highlight unique atmospheric dynamics within each layer.
• Discuss the role of the mesosphere in protecting Earth from meteoroids and how this impacts our atmosphere.
  • The mesosphere plays a crucial role in shielding Earth from meteoroids. As these objects enter Earth's atmosphere, they encounter air resistance that causes them to heat up and burn before reaching lower layers. This phenomenon prevents potential damage that could occur if meteoroids were to strike the surface. The destruction of meteoroids in this layer not only protects life on Earth but also maintains atmospheric integrity by reducing debris accumulation.
• Evaluate how the absence of significant gases in the mesosphere affects its overall atmospheric behavior compared to layers above and below.
  • The lack of significant gases such as ozone in the mesosphere leads to its unique thermal characteristics and behavior. Unlike the stratosphere that benefits from ozone's warming effects, the mesosphere remains cold due to its sparse gas composition. This absence influences atmospheric dynamics, including less convection compared to lower layers and a transition to increasing temperatures in the thermosphere above. The minimal gas presence creates conditions that are essential for meteorite disintegration and impacts how energy is distributed within Earth's atmosphere.

Related terms

Stratosphere:

The layer of the atmosphere located above the troposphere and below the mesosphere, known for its stable temperatures and the presence of the ozone layer.

Thermosphere: The layer above the mesosphere, characterized by increasing temperatures and containing the ionosphere, where auroras occur and satellites orbit.

Meteorites: Solid fragments from space that can enter Earth's atmosphere, typically burning up in the mesosphere due to friction with air.