Which greenhouse gas typically exists in both the stratosphere and the troposphere?

• A. Ozone (O_3)
• B. Carbon monoxide (CO)
• C. Nitrous oxide (N_2O)
• D. Methane (CH_4)

Answer: (A)

Verified step by step guidance

1. Understand the layers of the atmosphere: the troposphere is the lowest layer where weather occurs, and the stratosphere is the layer above it, containing the ozone layer.
2. Recall that ozone (O\_3) is a greenhouse gas that plays a crucial role in absorbing ultraviolet radiation in the stratosphere, forming the ozone layer.
3. Recognize that ozone also exists in the troposphere, where it acts as a pollutant and greenhouse gas, contributing to smog and warming.
4. Compare the other gases: carbon monoxide (CO), nitrous oxide (N\_2O), and methane (CH\_4) primarily exist in the troposphere and do not have significant concentrations in the stratosphere.
5. Conclude that ozone (O\_3) is the greenhouse gas that typically exists in both the stratosphere and the troposphere.