Which term describes the natural retention of heat in the atmosphere due to gases such as carbon dioxide and methane?

• A. Albedo effect
• B. Osmosis
• C. Greenhouse effect
• D. Solar reflection

Answer: (C)

The main concept is how certain atmospheric gases trap heat, keeping Earth warmer. This is the greenhouse effect: greenhouse gases such as carbon dioxide and methane absorb infrared radiation that is emitted from Earth after it absorbs sunlight. Instead of letting that heat escape back into space, these gases re-radiate it in all directions, including back toward the surface, which raises both surface and lower atmosphere temperatures. This natural trapping creates a comfortable climate baseline, but human activities have increased the concentration of these gases, strengthening the effect and warming the planet further.

Albedo relates to how much sunlight is reflected by surfaces, not heat retention by atmospheric gases. Osmosis is a cellular process about water movement, unrelated to atmospheric heating. Solar reflection is a general idea that overlaps with reflection concepts but isn’t the standard term for heat retention by greenhouse gases.