1. Spheres of Earth

The Surface of the Earth is a vast area of \(510\ \)million sq. km, where four spheres of the Earth interact. One can place everything in Earth's system into four major subsystems: Land, Water, Living things, or Air. These four subsystems are called "spheres." They are the "lithosphere" (land), "hydrosphere" (water), "biosphere" (living things), and "atmosphere" (air). Out of the four spheres, lithosphere, atmosphere, and hydrosphere are abiotic spheres. The biotic sphere is the biosphere. Together, these spheres constitute the planet Earth.

Land, i.e. the solid outer layer on which we live, is called Lithosphere--it consisting of Rocks and Soils. Earth Surface is highly uneven, ranging from high mountain ranges like the Himalayas, Rockies and Andes, to huge plains or flat areas like the Indo-Gangetic plain and deep valleys.

  

  

The water component of Earth is termed as Hydrosphere, which comprises all forms of water, i.e. solid, liquid, and gaseous water of Earth. The thickness of the Hydrosphere varies from \(10\ \)to \(20\ \)kilometres. The range of the Hydrosphere is from the Earth's surface to several kilometres into the Lithosphere and upward about 12 kilometres into the atmosphere. It consists of water bodies such as oceans, seas, rivers, lakes, ice caps on mountains and water vapour in the atmosphere.

  

Air envelope that surrounds the Earth is called Atmosphere. Different types of gases make up the atmosphere. The major gases are Nitrogen (\(78\)%) and Oxygen (\(21\)%). It also contains traces of other gases like Carbon dioxide, Hydrogen, Helium, Argon, and Ozone. The range of the atmosphere extends from less than \(1\)\(m\) below the Earth's surface to more than \(10,000\)\(km\) above the planet's surface. The atmosphere's upper layer protects the living organisms in the biosphere from the sun's ultraviolet radiation.

The narrow coexistence of the lithosphere, the hydrosphere and the atmosphere, where life exists, is known as Biosphere. It consists of distinct zones with their respective climate, plant and animal life. These zones are known as ecosystems.