Atmosphere and Climate.
Class 9 Geography – Detailed Notes Atmosphere and Climate 1. What is the Atmosphere? The atmosphere is the thin layer of gases surrounding the Earth. It is held around the Earth by the force of gravity. The atmosphere is essential for life because it: • Provides oxygen for respiration. • Provides carbon dioxide for photosynthesis. • Protects Earth from harmful solar radiation. • Maintains a suitable temperature for life. • Helps in the formation of clouds and rainfall. • Supports the water cycle and weather processes. PART A – ATMOSPHERE 2. Composition of the Atmosphere The atmosphere consists mainly of gases, water vapour and dust particles. Major gases Gas Approximate proportion Importance Nitrogen 78% Essential for plant growth and protein formation Oxygen 21% Necessary for respiration and combustion Argon 0.93% Inert gas Carbon dioxide About 0.04% Required for photosynthesis and helps regulate temperature Other gases Very small amounts Include ...