How does the greenhouse effect work?

How does the greenhouse effect work?

• A. Ozone depletion causes warming.
• B. Greenhouse gases trap heat by absorbing infrared radiation, warming Earth's surface.
• C. Greenhouse gases reflect sunlight back to space.
• D. The greenhouse effect is caused by water vapor dissolving in air.

Answer: (B)

The main idea is that certain gases in Earth’s atmosphere trap heat by absorbing infrared radiation. When sunlight warms the surface, it emits infrared energy. Greenhouse gases—like water vapor, carbon dioxide, and methane—absorb much of that infrared radiation and re-emit it in all directions, including back toward the surface. This trapping of heat keeps the lower atmosphere and surface warmer than they would be otherwise, which is the greenhouse effect in action. That’s why describing heat being trapped by infrared-absorbing gases and warming the surface is the best explanation. Other statements miss the mechanism: ozone depletion isn’t the warming cause in this context, greenhouse gases don’t primarily reflect sunlight back to space, and the idea that the effect comes from water vapor dissolving in air isn’t how it works.

The main idea is that certain gases in Earth’s atmosphere trap heat by absorbing infrared radiation. When sunlight warms the surface, it emits infrared energy. Greenhouse gases—like water vapor, carbon dioxide, and methane—absorb much of that infrared radiation and re-emit it in all directions, including back toward the surface. This trapping of heat keeps the lower atmosphere and surface warmer than they would be otherwise, which is the greenhouse effect in action.

That’s why describing heat being trapped by infrared-absorbing gases and warming the surface is the best explanation. Other statements miss the mechanism: ozone depletion isn’t the warming cause in this context, greenhouse gases don’t primarily reflect sunlight back to space, and the idea that the effect comes from water vapor dissolving in air isn’t how it works.