What is the greenhouse effect?

The greenhouse effect refers to the warming of the Earth's surface as a result of certain gases in the atmosphere trapping heat that would otherwise escape into space. These gases, often referred to as greenhouse gases, include carbon dioxide, methane, and water vapor. They allow sunlight to enter the atmosphere but prevent some of the heat from leaving, effectively creating a insulating layer. This process is essential for maintaining the Earth’s temperature at a level that supports life, as it keeps the planet warm enough to sustain ecosystems.

The other choices involve processes that either do not accurately describe the greenhouse effect or relate to different phenomena. The cooling of the Earth's surface and the reflection of sunlight by clouds do not involve the trapping of heat, and the evaporation of ocean waters is related to the water cycle rather than the mechanisms of heat retention that define the greenhouse effect. Understanding the greenhouse effect is crucial in the context of climate change, as an increase in greenhouse gas emissions enhances this natural process, leading to global warming and associated environmental impacts.