The atmosphere is the layer of gases surrounding Earth, composed mainly of nitrogen, oxygen and trace gases. It protects life by filtering harmful radiation, regulating temperature and enabling weather patterns. The atmosphere is essential for sustaining life, providing oxygen for respiration and carbon dioxide for photosynthesis.
Chapter 10 of Class 11 Physics focuses on thermal properties of matter. It covers concepts like temperature and heat and thermal expansion and specific heat capacity and calorimetry. The chapter also explains heat transfer methods such as conduction and convection and radiation. It includes laws of thermodynamics and ideal gas laws.
The greenhouse effect is the process by which certain gases in the Earth’s atmosphere, such as carbon dioxide (CO₂), methane (CH₄), and water vapor (H₂O), trap heat from the Sun. These gases allow sunlight to enter the atmosphere but prevent some of the outgoing infrared radiation from escaping back into space, keeping the planet warm.
Mechanism:
1. Sunlight enters the atmosphere, and the Earth’s surface absorbs it, warming up.
2. The heated surface radiates heat as infrared radiation. 3. Greenhouse gases absorb and re-emit some of this heat back towards the Earth’s surface.
This way, the temperature of the Earth is kept at a level which is favorable to life.
Significance:
1. It maintains the global temperature; otherwise, the Earth would be cold enough to not support life at an average temperature of about 15°C instead of -18°C without the greenhouse effect.
2. Supports ecosystems by providing thermal conditions necessary for biodiversity. 3. Enables liquid water to exist by preventing extreme cooling, which is essential for life.
Excessive greenhouse gases due to human activities can enhance this effect, causing global warming and significant environmental challenges.
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