Difference Between Weathering and Erosion

• Weathering is the breakdown of rocks into smaller pieces by physical, chemical, or biological processes, like freeze-thaw or rusting.
• Erosion is the movement of these broken pieces by natural forces like wind, water, or ice.

Illustration: Weathering occurs when rocks crack, while erosion happens when rivers carry those rocks away to form valleys.

Ecosystem Services and Their Valuation

Ecosystem services refer to the benefits humans receive from nature, like clean air, water, pollination, and climate regulation.

Valuation involves assigning monetary value to these services to highlight their importance in decision-making.

Illustration: Forests provide clean water and air; valuing these helps protect them from destruction, ensuring long-term environmental and economic benefits.

Photochemical Smog

Photochemical smog is a type of air pollution caused by the reaction of sunlight with pollutants like nitrogen oxides and volatile organic compounds (VOCs), primarily from vehicle exhausts. This reaction forms harmful chemicals such as ozone and peroxyacetyl nitrates (PANs).

Illustration: In cities like Los Angeles, heavy traffic and sunlight create smog, which can cause respiratory issues.

Conventional vs Non-Conventional Sources of Energy

• Conventional Energy: These are traditional energy sources like coal, oil, and natural gas, which are finite and pollute the environment.
• Non-Conventional Energy: These are renewable sources like solar, wind, and hydropower, which are sustainable and cleaner for the environment.

Illustration: Coal (conventional) vs solar power (non-conventional) for generating electricity.

Principle of Working of a Solar Cell

A solar cell works by converting sunlight into electricity through the photovoltaic effect. When sunlight hits the solar cell, it excites electrons in the material (usually silicon), causing them to move. This movement generates an electric current.

Illustration: Solar panels on rooftops use this process to power homes by converting sunlight into usable electrical energy.