Earth and Life Science Lesson 4

Subsystems of Planet Earth

• Earth comprises four interconnected subsystems: Atmosphere, Biosphere, Geosphere, and Hydrosphere, facilitating matter and energy flow.

Atmosphere

• Gaseous layer above Earth's surface, primarily composed of 78% nitrogen and 21% oxygen, with remaining gases (argon, CO2, CO, ozone) making up 1%.
• Supports life through oxygen for animals and carbon dioxide for plants; regulates climate by acting as a thermal blanket and a filter for solar radiation.

Layers of the Atmosphere

• Troposphere:

  • Extends 8-15 km above Earth's surface; where most weather occurs and contains 75% of the atmosphere's mass.
  • Temperature decreases with altitude, rich in water vapor.

• Stratosphere:

  • Ranges from 15 km to 50 km above Earth; contains the ozone layer that absorbs ultraviolet radiation.
  • Temperature increases with altitude due to ozone absorption.

• Mesosphere:

  • Extends from 50 km to 85 km above the surface; known for burning meteors upon entry.
  • Coldest layer with decreasing temperature with altitude.

• Thermosphere:

  • Extends from 85 km to over 600 km above the surface; temperature can reach 2,500°C (4,500°F).
  • Contains auroras and is where the International Space Station orbits.

• Exosphere:

  • Outermost layer extending from the top of the thermosphere to about 10,000 km.
  • Very thin air allows particles to travel long distances without colliding.

Biosphere

• Zone where all life forms exist, encompassing oceans, land, and freshwater ecosystems.
• Considered a thin layer of the Earth that hosts biodiversity.

Geosphere

• Solid structure of Earth, comprising the core, mantle, and crust.
• Represents all landforms and geological features of the planet.

Hydrosphere

• Encompasses all water on Earth, found in oceans, rivers, glaciers, and atmosphere.
• Oceans cover 71% of Earth's surface and hold 97.5% of its water, playing a crucial role in climate and life.