Earth's Atmosphere: Layers, Properties, and Solar Interactions

The Atmosphere is the gaseous layer that surrounds Earth. Its average weight is approximately 5.15 x 10¹⁸ kg (about 5.7 trillion tons).

Properties of the Atmosphere

The atmosphere exhibits various properties, both chemical and physical:

• Chemical Properties:
  • Oxidation
  • Reduction
• Physical Properties:
  • Mobility: Characterized by constant movement.
  • Compressibility: Atmospheric pressure changes with respect to density and temperature. Pressure generally decreases with increasing height and increases with decreasing height.
  • Expandability: Air expands as pressure decreases.
  • Transparency: It is colorless and odorless.
  • Diathermancy: It is transparent to solar radiation.
  • Shape: It conforms to the shape of the Earth.

The atmosphere is composed of gases and vapors, categorized as permanent and variable components.

The Biosphere

The Biosphere is the region of Earth where life exists, encompassing parts of the atmosphere, land, and oceans.

Layers of Earth's Atmosphere

Earth's atmosphere is divided into several distinct layers, each with unique characteristics:

• Troposphere

  This is the region in direct contact with the Earth's surface and the most dense area of the atmosphere. It contains approximately three-quarters of the atmospheric air and two-thirds of its total weight. Nearly all water vapor is found here. Temperature generally decreases with height, and convective motions occur. Density also decreases with height, and this layer produces the greatest amount of severe weather.

• Stratosphere

  The stratosphere is a more stable layer where temperature generally increases with height due to the absorption of solar radiation. It contains the greatest amount of stratospheric ozone (O₃), which absorbs harmful ultraviolet (UV) radiation. This ozone layer is being affected by air pollution. There is little water vapor and minimal precipitation in this layer. It is also known as the chemosphere and the ozone layer due to its significant chemical activity.

• Mesosphere

  Extending from approximately 50 to 100 km, the mesosphere experiences a decrease in pressure with altitude. The air is very dry, and solar radiation dissociates the existing small amount of water vapor.

• Thermosphere

  This layer extends to approximately 500 km in height. Solar radiation is direct, and the temperature increases significantly. Chemical reactions within this layer are very violent.

• Exosphere

  The exosphere extends to a maximum height of approximately 1,050 km. It is primarily formed by light ions like hydrogen and helium, which can escape into space.

• Magnetosphere

  Located at approximately 55,000 km, the magnetosphere shields Earth from harmful ionic radiation from space.

Atmospheric Radiation and Solar Energy

The principal source of atmospheric radiation is the Sun, with a surface temperature of approximately 15 million degrees Celsius. The energy from the Sun reaches Earth in the form of electromagnetic waves, which include:

• Gamma Rays
• X-rays
• Ultraviolet (UV) light
• Visible light
• Infrared (IR) radiation
• Microwaves
• Radio waves

Atmospheric Processes and Solar Radiation Interaction

Solar radiation undergoes several phenomena upon interacting with Earth's atmosphere:

• Absorption
• Dispersion
• Reflection

Atmospheric Photochemical Processes: Life primarily occurs within the troposphere, especially within the biosphere. These processes involve the formation and interaction of molecules, radicals, and ions.