Mesosphere

Definition

The mesosphere is the third layer of Earth's atmosphere, situated above the stratosphere and below the thermosphere, ranging from about 50 to 85 kilometers above sea level. This layer is characterized by a decrease in temperature with increasing altitude, which can drop to as low as -90°C, making it the coldest atmospheric layer. The mesosphere plays a crucial role in atmospheric processes and is where most meteoroids burn up upon entering the Earth's atmosphere.

5 Must Know Facts For Your Next Test

1. The mesosphere extends from approximately 50 km to 85 km above Earth's surface, representing a transition zone between the lower and upper atmosphere.
2. Temperature in the mesosphere decreases with altitude, reaching its lowest point at the top of the layer, where conditions are extremely cold.
3. This layer is where most meteors burn up upon atmospheric entry, creating bright streaks of light known as 'shooting stars.'
4. The mesosphere is also difficult to study directly because it lies above commercial aircraft and weather balloons' operational altitudes.
5. Waves generated by gravity can propagate through the mesosphere, affecting its dynamics and contributing to various atmospheric phenomena.

Review Questions

• How does temperature change with altitude in the mesosphere, and what implications does this have for atmospheric processes?
  • In the mesosphere, temperature decreases with altitude, which contrasts with the temperature profile of the stratosphere below it. This significant temperature drop results in colder conditions that influence weather patterns and atmospheric dynamics. Additionally, this cooling contributes to the layer's role in meteoroid disintegration, as it provides an environment where intense friction occurs when meteoroids enter.
• Evaluate the significance of the mesosphere in protecting Earth from meteoroids and its role in atmospheric dynamics.
  • The mesosphere plays a vital protective role by being the primary layer where meteoroids burn up due to friction with atmospheric gases. This incineration prevents potential impacts on Earth’s surface. Furthermore, the dynamic processes within this layer, including gravity waves and turbulence, contribute to overall atmospheric circulation and climate patterns that affect weather systems across the planet.
• Synthesize information about how our understanding of the mesosphere has evolved over time and what future research might focus on.
  • Our understanding of the mesosphere has advanced significantly with technology improvements such as satellite observations and ground-based radar systems. Initially difficult to study due to its altitude and harsh conditions, researchers are now focusing on how changes in this layer might influence global weather patterns and climate change. Future research will likely explore interactions between the mesosphere and other atmospheric layers, providing insights into broader atmospheric phenomena like sudden stratospheric warming events.

Related terms

Stratosphere:

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

Thermosphere: The layer above the mesosphere, characterized by increasing temperatures due to absorption of high-energy solar radiation, and home to the ionosphere.

Meteoroids: Small rocky or metallic bodies in outer space that can enter Earth’s atmosphere, often burning up in the mesosphere and creating meteor streaks.