Stratosphere

Definition

The stratosphere is the second layer of Earth's atmosphere, located above the troposphere and below the mesosphere, extending from about 10 to 50 kilometers above the Earth's surface. This layer is characterized by a gradual increase in temperature with altitude, primarily due to the absorption of ultraviolet (UV) radiation by ozone, which is concentrated in the ozone layer found within this region.

5 Must Know Facts For Your Next Test

1. The stratosphere contains the ozone layer, which plays a crucial role in absorbing the majority of the sun's harmful ultraviolet radiation.
2. In contrast to the troposphere, temperatures in the stratosphere increase with altitude due to the absorption of UV radiation by ozone, leading to a stable atmospheric structure.
3. Commercial jet aircraft typically fly in the lower stratosphere to avoid turbulence found in the troposphere.
4. The boundary between the troposphere and stratosphere is called the tropopause, where a temperature inversion occurs.
5. Stratospheric clouds, such as polar stratospheric clouds, can form at very high altitudes and play a role in ozone depletion.

Review Questions

• How does the temperature profile of the stratosphere differ from that of the troposphere, and what implications does this have for atmospheric stability?
  • In the troposphere, temperature decreases with altitude, which contributes to atmospheric instability and weather phenomena. In contrast, in the stratosphere, temperature increases with altitude due to ozone absorption of UV radiation. This temperature inversion leads to a more stable atmosphere in the stratosphere, preventing vertical mixing and resulting in clearer skies and less turbulent air.
• Discuss the significance of the ozone layer within the stratosphere and its impact on life on Earth.
  • The ozone layer is vital because it absorbs approximately 97-99% of harmful UV radiation from the sun. Without this protective layer, life on Earth would be exposed to increased levels of UV radiation, leading to higher risks of skin cancer, cataracts, and negative impacts on ecosystems. The presence of the ozone layer enables life to thrive on land and supports various biological processes essential for survival.
• Evaluate the consequences of human activities on stratospheric ozone levels and how these changes affect environmental and public health.
  • Human activities, particularly the release of chlorofluorocarbons (CFCs) and other ozone-depleting substances, have significantly reduced stratospheric ozone levels, leading to an increase in UV radiation reaching Earth's surface. This alteration has serious consequences for environmental health, including increased rates of skin cancer and adverse effects on marine ecosystems due to changes in phytoplankton populations. Furthermore, these changes can disrupt food chains and biodiversity, making it critical to monitor and regulate substances that harm the ozone layer.

Related terms

Troposphere: The lowest layer of the atmosphere where weather occurs, extending from the Earth's surface up to about 10 kilometers.

Ozone Layer: A region within the stratosphere that contains a high concentration of ozone (O₃) molecules, which absorb and protect life on Earth from harmful UV radiation.

Mesosphere: The layer of the atmosphere located above the stratosphere, extending from about 50 to 85 kilometers, where temperatures again decrease with altitude.