Earth's Four Subsystems: Spheres Overview

Study Notes

Subsystems of Earth

Earth has four primary subsystems, known as spheres: lithosphere (land), hydrosphere (water), biosphere (living things), and atmosphere (air).

Atmosphere

Composed of all Earth's gases, with the most abundant being nitrogen.
The Karman line serves as an imaginary boundary separating the atmosphere from outer space.
Comprised of five layers:
- Troposphere: Extends up to 14.5 km above Earth, where weather disturbances occur.
- Stratosphere: Ranges from 14.5 to 50 km; contains the ozone layer that protects against UV radiation.
- Mesosphere: Spans 50 to 85 km above the surface; shields Earth from space debris and experiences the coldest temperatures, around -90°C.
- Thermosphere: From 85 to 600 km; contains charged particles that create auroras. Many satellites orbit within this layer.
- Exosphere: Outermost layer extending to about 10,000 km; no definitive boundary between this layer and space.

Geosphere

Derived from the Greek word "geo," meaning ground; includes all soil, rocks, and minerals from Earth's crust to core.
Divided into three main layers: crust, mantle, and core.
- Crust: Outermost layer; consists of oceanic and continental crust.
  - Oceanic crust is 5 to 10 km thick, located beneath the oceans.
  - Continental crust is thicker, between 15 and 70 km, forming the continents.
- Mantle: Located beneath the crust; divided into layers based on mineral composition and tectonic deformation.
  - Asthenosphere: Below the lithosphere, allowing for the movement of tectonic plates.
- Core: Innermost layer with a radius of 3,480 km, primarily composed of iron and nickel.
  - Consists of an outer core and an inner core, separated by the Bullen discontinuity.

Hydrosphere

Comes from the Greek word "hydro," meaning water; includes all water on Earth in various forms: vapor, liquid, and ice.
Dominated by 97.5% saltwater, while only 2.5% is freshwater.
Encompasses oceans, lakes, rivers, marshes, clouds, and rain.

Biosphere

Originates from the Greek word "bio," meaning life; consists of all living organisms, including microbes, plants, and animals.
Extends to the upper atmosphere (where insects and birds exist) and deep ocean areas (where marine life thrives).
Organisms interact within ecosystems, forming communities referred to as biomes, which are found globally.
Notable biomes include deserts, tropical rainforests, swamps, and coral reefs.

Summary of Key Points

Four primary subsystems of Earth are atmosphere, geosphere, hydrosphere, and biosphere.
Atmosphere is gaseous; geosphere covers all soil and rock; hydrosphere contains all water bodies; biosphere comprises all living organisms.
Examples:
- Atmosphere: Oxygen gas, neon lights, aurora borealis.
- Geosphere: Mayon Volcano, Mango, Batanes Islands.
- Hydrosphere: Pasig River, Laguna de Bay.
- Biosphere: Bacteria, organisms interacting within biomes.

Description

Explore the four essential subsystems of Earth known as spheres: lithosphere, hydrosphere, biosphere, and atmosphere. This quiz will help you understand the characteristics and boundaries of each sphere, including the composition of the atmosphere and its significance. Test your knowledge about how these spheres interact with each other.