The Earth’s Crust, The Mantle, The Core and their Respective Characteristics

Consists of four main layers:

• Atmosphere
• Hydrosphere
• Lithosphere (Landmass)
• Biosphere

Atmosphere

1. A thin layer of gases held around the earth by gravitational attraction.

2. Composed of:

   • Abiotic components (non-living matter):
     • Mixture of gases (Nitrogen, Oxygen, Argon, Carbon dioxide).
     • Water vapor.
     • Dust particles.
   • Biotic components (living organisms):
     • Microscopic organisms like bacteria.

Composition of the atmosphere

1. Mixture of gases:
   • Nitrogen (78%)
   • Oxygen (21%)
   • Argon (0.009%)
   • Carbon dioxide (0.03%)
2. Water vapor:
   • Colorless, odorless, and forms a perfect mixture with gases.
3. Biota components:
   • Includes microscopic organisms like bacteria.

Structure of the atmosphere

Divided into two zones based on temperature changes:

• Homosphere
• Heterosphere

Homosphere (0–80 km above sea level)

1. Composed of uniform gases and temperature.

2. Divided into three layers:

   • Troposphere:
     • Extends from 0–15 km.
     • Nearest to Earth.
     • Contains water vapor, gases, and dust.
     • Supports life (plenty of oxygen).
   • Stratosphere:
     • Extends from 15–48 km.
     • Lies above the tropopause.
     • Contains water vapor, dust particles, and gases.
     • High concentration of ozone gas.
   • Mesosphere:
     • Extends from 48–80 km.
     • Temperature decreases with altitude.
     • Separated from stratosphere by stratopause.
     • Upper boundary is called mesopause.

Heterosphere (Above 80 km towards space)

1. Extends into interplanetary space.

2. Divided into two layers:

   • Thermosphere:
     • Temperature increases with altitude.
     • Lacks water vapor and dust.
     • Contains ions (affect radio communication).
   • Exosphere:
     • Found above the thermosphere.
     • Very high temperatures but little research conducted.

1. Insulation:
   • Acts as an insulator or shield, regulating temperature during the night and winter.
2. Solar Filtering:
   • Filters solar radiation.
   • Prevents harmful ultraviolet (UV) rays of certain wavelengths from reaching the Earth's surface due to the ozone layer in the stratosphere.
3. Scientific Function:
   • Acts as a medium for scientific experiments and observations.
   • Example: The ionosphere reflects some electromagnetic waves and radio signals back to Earth.
4. Support for the Hydrological Cycle:
   • Facilitates processes such as surface water evaporation, condensation, and precipitation formation.
5. Support for Life:
   • Provides essential gases like oxygen necessary for living organisms.
   • Atmospheric pressure, due to the weight of air, enables breathing.
   • Variations in atmospheric pressure cause wind movement and influence temperature, humidity, and precipitation.

1. Refers to the layer consisting of all water bodies on Earth.
2. Includes oceans, rivers, precipitation, and underground water.
3. Covers approximately 75% of the Earth's surface.

1. The solid part of the Earth.
2. Includes various landforms such as mountains, valleys, and plateaus.
3. Also known as the crust.
4. Composed of:
   • Continents (major land masses)
   • Islands (minor land masses)

1. A complex zone that includes all living things.
2. Encompasses parts of:
   • The lower atmosphere,
   • The upper lithosphere,
   • And the upper hydrosphere.
3. Receives energy from the sun, providing conditions necessary for life.
4. Unique to Earth, not found elsewhere in the solar system.

1. Composed of elements, minerals, and rocks.
2. These materials vary in physical and chemical properties.

Elements

1. Smallest particles of matter that cannot be split into other forms.
2. Examples include:
   • Magnesium
   • Potassium
   • Sodium
   • Iron
   • Aluminum
   • Silicon

Minerals

1. Naturally occurring substances.
2. Have definite shape, color, and resistance.
3. Formed through the combination of different elements.