• Anything in Earth's system can be placed into one of four major subsystems: land, water, living things, or air.
  • These four subsystems are called as "Spheres".
Four important spheres/ realms of earth to support life on Earth are:
  • Land on which we live.
  • The solid outer layer of the earth consisting of Rocks and Soils.
  • The surface of the lithosphere (Earth surface) is very uneven.
  • There are high mountain ranges like the Himalayas, Rockies and Andes, huge plains or flat areas like the Indo-Gangetic plain and deep valleys.
  • The Hydrosphere comprises of all the solid, liquid, and gaseous water of Earth.
  • Thickness of hydrosphere: \(10\) to \(20\) kilometres
  • The range of Hydrosphere is from the Earth's surface to several kilometres into the lithosphere and upward about \(12\) kilometres into the atmosphere.
  • Consists of water bodies such as oceans, seas, rivers, lakes, ice caps on mountains and water vapour in the atmosphere.