NCERT Solutions for Class 9th Social Science Chapter 3 Atmosphere and Climate

About this chapter

The atmosphere is the blanket of air held around the Earth by gravity . Fig. 3.2 gives its composition: nitrogen 78% , oxygen 21% , argon 0.93%, carbon dioxide 0.04% and other gases 0.03% — which add to exactly 100% — plus water vapour (0.1–0.4%) and dust on top of that. It shields us from harmful radiation including ultraviolet, and regulates temperature by trapping some of the Sun's energy. The atmosphere is layered , and the layers are defined by how temperature and density change with altitude . Density is highest at the surface and falls with height. Temperature falls with height in the troposphere (about 12 km, where nearly all weather happens) and in the mesosphere (to 80 km, where meteors burn up), and rises with height in the stratosphere (to 50 km, because ozone absorbs ultraviol

• Chapter opening
• The chapter's opening paragraph
• A world with no atmosphere
• Composition of the Atmosphere
• Weather and Climate
• Wind
• Table 3.1, Wind speeds and their common effects
• Watching the weather change over two weeks
• Traditional Indian seasons (Table 3.2)
• Monsoon