Introduction

The Earth has four major domains that interact with one another to support life:

1. Lithosphere: The solid surface of the Earth.
2. Atmosphere: The layer of gases surrounding the Earth.
3. Hydrosphere: All water bodies on the Earth.
4. Biosphere: The part where life exists, integrating the other three domains.

These domains are interconnected and essential for the existence of life on Earth.

The Lithosphere

1. The lithosphere is the solid, rocky outer layer of the Earth that includes the crust and the upper part of the mantle.
2. It forms the Earth’s landmasses (continents and islands) and ocean floors.
3. It is uneven, with mountains, plains, plateaus, and valleys.

Continents

The lithosphere includes seven continents, each unique in size, geography, and features:

1. Asia:
   1. Largest and most populous continent.
   2. Covers one-third of the Earth’s total land area.
   3. Features: Himalayas, Gobi Desert, and large river systems like the Ganges and Yangtze.
2. Africa:
   1. Second largest continent.
   2. Known for the Sahara Desert (largest hot desert) and the Nile River (longest river in the world).
3. North America:
   1. Bordered by the Arctic Ocean in the north, Atlantic Ocean in the east, and Pacific Ocean in the west.
   2. Home to the Great Lakes and the Rocky Mountains.
4. South America:
   1. Known for the Amazon Rainforest and Andes Mountains.
   2. The Amazon River is the second-longest river globally.
5. Antarctica:
   1. Located around the South Pole.
   2. Entirely covered in thick ice sheets.
   3. No permanent human population, only scientific research stations.
6. Europe:
   1. Small in size but highly developed economically and culturally.
   2. Shares a continuous landmass with Asia (referred to as Eurasia).
7. Australia:
   1. Smallest continent, often referred to as an island continent.
   2. Features: The Great Barrier Reef and vast deserts like the Outback.

The Atmosphere

1. The atmosphere is the layer of gases that surrounds the Earth.
2. It protects life on Earth by absorbing harmful solar radiation and regulating temperature.
3. It also contains the oxygen we breathe and carbon dioxide needed for plants.

Layers of the Atmosphere

1. Troposphere:
   1. Closest to Earth’s surface.
   2. Weather phenomena like clouds, rain, and storms occur here.
2. Stratosphere:
   1. Contains the ozone layer, which absorbs harmful ultraviolet rays from the Sun.
3. Mesosphere:
   1. Protects the Earth by burning up meteoroids.
4. Thermosphere:
   1. Hosts phenomena like the Northern and Southern Lights (Auroras).
5. Exosphere:
   1. The outermost layer that merges with space.

Composition of Air

1. Nitrogen: 78%
2. Oxygen: 21%
3. Other Gases: Argon, carbon dioxide, and traces of others.

The Hydrosphere

1. The hydrosphere includes all the water bodies on Earth, such as oceans, seas, rivers, lakes, glaciers, and underground water.
2. Water covers about 71% of the Earth’s surface.

Major Oceans

1. Pacific Ocean:
   1. Largest and deepest ocean.
   2. Covers one-third of the Earth’s surface.
2. Atlantic Ocean:
   1. Second largest ocean.
   2. Contains the world’s busiest shipping lanes.
3. Indian Ocean:
   1. Known for its triangular shape.
   2. Bordered by Asia, Africa, and Australia.
4. Southern Ocean:
   1. Surrounds Antarctica and merges with the Pacific, Atlantic, and Indian Oceans.
5. Arctic Ocean:
   1. Smallest and shallowest ocean.
   2. Located in the Arctic region around the North Pole.

The Biosphere

1. The biosphere is the narrow zone of Earth where land, air, and water interact to support life.
2. It includes plants, animals, and microorganisms.

Interaction of Domains

1. Life exists where the lithosphere, atmosphere, and hydrosphere meet.
2. Forests grow on land (lithosphere) and release oxygen (atmosphere).
3. Rivers and oceans (hydrosphere) support aquatic life.

Human Impact

1. Human activities like deforestation, industrialization, and pollution are harming the biosphere.
2. Conservation of natural resources is essential for sustaining life.

Important Terms to Remember

1. Lithosphere: The solid crust of the Earth, including continents and ocean floors.
2. Atmosphere: The layer of gases protecting and sustaining life.
3. Hydrosphere: All water bodies, essential for life and climate regulation.
4. Biosphere: The zone of life, where land, water, and air meet.
5. Continents: Large landmasses (Asia, Africa, North America, South America, Antarctica, Europe, and Australia).
6. Oceans: Large water bodies (Pacific, Atlantic, Indian, Southern, Arctic).