Chapter 1.2
Earth’s Spheres
Earth
• The only planet currently known to support
life.
• This capacity is due to the interactions
among its 4 spheres…
– Atmosphere
– Hydrosphere
– Geosphere
– Biosphere
Sphere #1
THE ATMOSPHERE
What Is the Atmosphere?
• A mixture of gases, mostly nitrogen (N)
and oxygen (O) with smaller amounts of
argon, carbon dioxide, and other gases
• Held to the Earth by gravity
• Thins with altitude
Why Is the Atmosphere
Important?
• Supports Life
– Animals need oxygen
– Plants need carbon dioxide (CO2)
• Regulates Climate
– Retains heat at night
– Shields from sun’s radiation during the day
– Wind transports heat from Equator and cold
from Poles
Sphere #2
Geosphere
The Geosphere
• The solid Earth
– Rocks, mountains, beaches, ocean basins,
magma, mantle
• The geosphere is slowly changing
– Volcanic eruptions form new land
– Mountains are uplifted
– Continents are in slow but constant motion
Sphere #3
THE HYDROSPHERE
What Is the Hydrosphere?
• All the earth’s water
• Most of this water is salt water
• 3% of the hydrosphere contains fresh
water
– Most of this water is frozen in glaciers
– Remaining water is found in groundwater,
lakes, water vapor, and river water.
• All the water on Earth is recycled…
– No new water is ever created!
Sphere #4
THE BIOSPHERE
What Is the Biosphere?
• The zone inhabited by life
– Includes the uppermost geosphere, the
hydrosphere, and lower atmosphere
• Includes all forms of life
– Single-celled protozoans, to jellyfish to
redwood trees to people.