Mesosphere

Definition

The mesosphere is a layer of Earth's atmosphere located above the stratosphere and below the thermosphere, extending from about 50 kilometers (31 miles) to approximately 85 kilometers (53 miles) above sea level. This layer is characterized by decreasing temperatures with increasing altitude, which play a crucial role in atmospheric dynamics and phenomena such as meteor trails and noctilucent clouds.

5 Must Know Facts For Your Next Test

1. In the mesosphere, temperatures can drop to as low as -90 degrees Celsius (-130 degrees Fahrenheit), making it the coldest layer of the atmosphere.
2. The mesosphere is where most meteors burn up upon entering Earth’s atmosphere, resulting in visible meteor showers.
3. This atmospheric layer is also home to noctilucent clouds, which are rare and only visible during twilight when sunlight illuminates ice crystals at high altitudes.
4. Due to its altitude and conditions, the mesosphere is difficult to study directly with weather balloons or aircraft, making satellite observation critical for understanding this layer.
5. The boundary between the mesosphere and the thermosphere is known as the mesopause, which marks a significant temperature change as one moves into higher altitudes.

Review Questions

• Explain how temperature changes in the mesosphere affect atmospheric phenomena such as meteors and noctilucent clouds.
  • In the mesosphere, temperatures decrease with altitude, reaching extremely low values. This significant drop in temperature contributes to meteors burning up upon entering this layer due to friction with air molecules. Additionally, these cold temperatures create conditions that allow for noctilucent clouds to form, as they consist of ice crystals that are illuminated by sunlight when positioned at high altitudes during twilight.
• Discuss the challenges researchers face when studying the mesosphere and the methods they use to overcome these obstacles.
  • Studying the mesosphere presents challenges primarily due to its altitude, where traditional weather balloons and aircraft cannot reach. Researchers often rely on satellite observations and radar techniques to gather data about this elusive layer. These methods provide insights into temperature profiles, atmospheric composition, and phenomena occurring in the mesosphere without needing direct access.
• Evaluate the impact of human activities on atmospheric layers, including how changes in emissions might influence conditions in the mesosphere.
  • Human activities have a profound impact on atmospheric layers through emissions of greenhouse gases and pollutants. While most direct effects are observed in lower layers like the troposphere and stratosphere, changes in composition can influence temperatures and dynamics even in the mesosphere. For instance, increased greenhouse gas concentrations could alter circulation patterns and thermal structures at high altitudes, potentially affecting meteor activity and cloud formation processes in this layer.

Related terms

Stratosphere: The second layer of Earth's atmosphere, situated above the troposphere and below the mesosphere, known for its temperature inversion and the presence of the ozone layer.

Thermosphere: The layer of the atmosphere above the mesosphere, characterized by extremely high temperatures and the presence of ionized gases, where phenomena like auroras occur.

Meteor: A small celestial body that enters Earth's atmosphere, becoming visible as a bright streak of light due to frictional heating in the mesosphere.