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Wink Notes
B.Tech CSE — 2nd Semester
Environmental Studies
— Unit - 5 —
1. The Greenhouse Effect
The Greenhouse Effect is a completely natural, essential physical process. Without it, the Earth's average temperature would be a frozen -18°C, and all life would die. The problem is not the effect itself, but humanity 'enhancing' it to catastrophic levels.
The Mechanism
- The Sun emits short-wave, high-energy UV and visible light. This easily passes through our atmosphere and hits the Earth, heating the ground.
- The warm Earth radiates that heat back toward deep space as long-wave Infrared (IR) radiation.
- However, certain gases in the atmosphere (Greenhouse Gases) are physically opaque to long-wave IR. They block the heat from escaping into space, absorbing it and reflecting it back down to Earth. This acts like the glass walls of a botanical greenhouse, trapping heat.
The Major Greenhouse Gases (GHGs)
Carbon Dioxide (CO2) is the most famous, driven by burning coal and oil. Methane (CH4), generated by cattle flatulence and rotting landfills, is 25 times more powerful at trapping heat than CO2. Nitrous Oxide (N2O) from synthetic agricultural fertilizers is 300 times more powerful. Chlorofluorocarbons (CFCs) from old refrigerators are 10,000 times more powerful.