English: This diagram shows the Earth's "greenhouse effect." The Earth absorbs some of the energy it receives from the sun and radiates the rest back toward space. However, certain gases in the atmosphere, called greenhouse gases, absorb some of the energy radiated from the Earth and trap it in the atmosphere. These gases essentially act as a blanket, making the Earth’s surface warmer than it otherwise would be. While this greenhouse effect occurs naturally, making life as we know it possible, human activities in the past century have substantially increased the amount of greenhouse gases in the atmosphere, causing the atmosphere to trap more heat and leading to changes in the Earth’s temperature.

Summary of diagram:

1. Energy from the sun arrives to the Earth as solar radiation.
2. Some solar radiation is reflected by the Earth and the atmosphere. Most radiation is absorbed by the Earth's surface and warms it.
3. Infrared (heat) radiation is emitted by the Earth's surface. Some of the infrared radiation passes through the atmosphere. Some is absorbed and re-emitted in all directions by greenhouse gas molecules. The effect of this is to warm the Earth's surface and the lower atmosphere.

This image description is copied from the cited public-domain source, pages 3 ("Introduction") and 11 ("Greenhouse Gases").