NCERT Solutions for Class 9th Science Chapter 13 Earth as a System: Energy, Matter, and Life

About this chapter

The Earth is a single system of five interacting spheres — geosphere (rock, soil, interior), hydrosphere (liquid water), cryosphere (ice and snow), atmosphere (air) and biosphere (all life). A disturbance in one sphere shows up as a change in the others. Solar radiation reaches us as electromagnetic waves travelling at 3 × 10 8 m s –1 through vacuum. About 99 per cent of the Sun's energy lies in the UV, visible and infrared bands. The solar constant is 1.4 kW m –2 (1400 J s –1 m –2 ); after absorption and scattering, the maximum insolation at the surface is about 1 kW m –2 . Heating is uneven because of albedo (snow reflects 0.80 – 0.90, black soil and ocean water reflect very little), because of latitude (the same beam is spread over a larger area near the poles) and because of the tilt o

• Chapter opener
• Introduction
• Lead-in to 13.1 Uneven Heating of the Earth
• .1 Uneven Heating of the Earth
• .1.1 Interaction of solar radiation on the Earth's surface
• .1.3 Role of the atmosphere
• Why is the ozone layer so important?
• .2.1 Local winds / 13.2.3 Ocean currents
• .3.2 Carbon cycle
• .3.4 Oxygen cycle