Warming in the stratosphere is mainly caused by:

Absorption of ultraviolet radiation by ozone
Release of latent heat energy during condensation
Chemical reactions between ozone and chlorofluorocarbons
Frictional heating caused by meteorites

The correct answer is: A. Absorption of ultraviolet radiation by ozone.

The stratosphere is the second layer of Earth’s atmosphere, above the troposphere and below the mesosphere. It is located from approximately 10 to 50 kilometers (6 to 31 miles) above Earth’s surface. The stratosphere is characterized by an increase in temperature with altitude, due to the absorption of ultraviolet radiation by ozone.

Ozone is a molecule that consists of three oxygen atoms. It is formed in the stratosphere when ultraviolet radiation splits oxygen molecules into two oxygen atoms. These oxygen atoms then react with oxygen molecules to form ozone. Ozone absorbs ultraviolet radiation, which prevents it from reaching the Earth’s surface. This absorption of ultraviolet radiation is what causes the stratosphere to warm.

The other options are incorrect because:

  • Option B is incorrect because the release of latent heat energy during condensation occurs in the troposphere, not the stratosphere.
  • Option C is incorrect because chemical reactions between ozone and chlorofluorocarbons occur in the troposphere, not the stratosphere.
  • Option D is incorrect because frictional heating caused by meteorites is negligible in the stratosphere.