The earth has four main spheres – the geosphere, atmosphere, hydrosphere and biosphere. Each system is unique, and each interacts with the other. Today we will try to know definitions of all these spheres with help of some pictures.
Geosphere
Geosphere is the area from the surface of Earth down to its center. It is divided into three main parts :- the crust, mantle and core. The rigid outer shell of earth is called the crust. There are two kinds of crusts –
- Continental crust
- Oceanic crust.
Just below the crust is Earth’s mantle. The mantle differs from the crust both in composition and behavior. The mantle differs from the crust both in composition and behavior. The mantle ranges in temperature from 100°C to 4000°C – much warmer than the temperature found in Earth’s crust.
It contains semi fluid hot molten rock material magma. Below the mantle is Earth’s core. The core is further divided into outer core and inner core. The outer core is fluid in nature comprising iron and nickel. The inner most layer is called inner core, which is a solid iron ball.
Lithosphere
Lithosphere is a part of geosphere and comprises crust and upper mantle. The lithosphere or the crustal layer includes three kinds of rocks :-
- Igneous rocks or Primary rocks.
- Sedimentary rocks or Secondary rocks.
- Metamorphic rocks or Tertiary rocks.
Atmosphere
Atmosphere, the blanket of gases that surrounds our planet is called the atmosphere. Earth’s atmosphere contains about 78% nitrogen and 21% oxygen. The remaining 1 percent of gases in the atmosphere includes water vapor, argon, carbon dioxide and other trace gases. Earth’s atmosphere provides oxygen for living things, protects Earth’s inhabitants from harmful radiation from the Sun, and helps to keep the planet at a temperature suitable for life. Ozone layer acts as a protection layer for reflected cosmic rays towards the Sun.
Hydrosphere
Hydrosphere, all the water on Earth, including the water in the atmosphere, makes up the hydrosphere. About 97% of Earth’s water exists as salt water, while the remaining 3% is freshwater contained in glaciers, lakes and rivers and beneath Earth’s surface as groundwater. Only a fraction of Earth’s total amount of freshwater is in lakes and rivers.
Biosphere
Biosphere includes all organisms on Earth as well as the environments in which they live. Most organisms live within a few meters of Earth’s surface, but some exist deep beneath the ocean’s surface, and others live high atop Earth’s mountains. All of Earth’s life forms require interaction with at least one or other systems for their survival.
All notes are available here >> Physical Geography