Four Subsystems of the Earth

Lesson 2| Four Subsystems of the Earth
Subsystem is a small system contained in a bigger or broader one. Earth consists of systems that coexist and
interact in one way or another. The 4 subsystems of Earth are geosphere, hydrosphere, atmosphere, and biosphere.
GEOSPHERE
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Solid sphere of the Earth
Geologic processes (volcanic activity, formation of mountains, volcanoes, and other geologic structures takes
place)
Lithosphere – part of geosphere that is composed of the solid, outermost part of the planet; tectonic plates move,
are found, causing the ground to move through vibrations of energy from the mantle.
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Not a continuous layer
Divided into larger number of huge plates that move in relation
Pangaea – Alfred Weneger (plates drift sideways at the rate of 12 cm/layer
Tectonic plates – border between tectonic plates are boundaries
o Convergent – separate
o Divergent – one is going down
o Transform boundaries – horizontal (earthquakes)
Are continents the same as plates?
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No. Continents are part of the plates, same occur in the middle of plates, not at their boundaries or edges.
Example: Asia – Eurasian plate, North American plate, Arabian plate, Indo-Australian plate
Continents have moved by riding on the tops of plates
How many continents?
1.
2.
3.
4.
5.
6.
7.
North America
South America
Europe
Asia
Africa
Antarctica
Australia
HYDROSPHERE
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All the waters on earth (liquid water found in oceans, lakes, and streams; solid form – polar ice; water vapor that
results from evaporation of liquid water)
71% of earth’s water is ocean
Other fractions are distributed in polar ice and water vapor
Ocean vs. Sea
Sea – part of an ocean and partially surrounding by land
Ocean – body of salt water with almost no boundaries and limitless volume
(Energy from the sun heats up the ocean water unevenly due to the difference in the angle of sun’s rays across different
portions of the earth – cause difference in ocean temperature)
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Lesson 2| Four Subsystems of the Earth
Ocean waters near the equator is warm, water near the poles is cold – difference in the temperature of the
planet’s water – difference in density thus, water to move by means of convection
Convection Current – distributes energy in the ocean
• Lighter (less dense) – warm material rises
• Heavier (denser) – cool material sinks
ATMOSPHERE
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Gaseous part of the Earth
Composed of several trace gases necessary to support the existence of all living components
Gases:
• Nitrogen – 71%
• Oxygen – 20.9%
• Argon – 0.90%
• Carbon Dioxide – 0.03%
• Other gases – 0.17%
Divided into layers according to differences in the pattern of temperature as one goes to higher altitude
Layers of the Atmosphere
o Troposphere
– Lowest layer
– Most of the water vapor
– All weather associated cloud types
– Temperature decreases as altitude increases
– Higher altitude – atmosphere becomes thinner and absorbs less solar radiation
– Temperature stops decreasing at the tropopause – found at the top of the troposphere
o Stratosphere
– Temperature increases – due to the presence of ozone (absorb UV rays)
– Jet planes fly
– Top of stratosphere (stratopause) – temperatures stop increasing
– Free of clouds and other forms of weather
o Mesosphere
– Layer with decreasing temperature as altitude increases
– Coldest region – upper mesosphere (mesopause)
– Protect from meteoroids – most meteoroids burn up (burning meteoroid – shooting
star/burning meteors) due to the intense friction that builds up between to air and the
meteoroid (manage to reach earth are called meteorites)
o Thermosphere
– Temperature rising (thermopause)
– Satellites are placed
o Exosphere
Maintains the planet’s temperature, acts as a thermostat
Also plays a role in weathering of rocks
Sun evenly heats the air which leads to the movement of air molecules
Cold air sinks at the bottom of the atmosphere – high density; hot air rises – low density
(Distributes energy in the atmosphere; movement of air in the atmosphere that causes weather and climate)
Lesson 2| Four Subsystems of the Earth
BIOSPHERE
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Encompasses all life forms
Organisms comprising the simplest cyanobacteria to the complex eukaryotes adapt to their natural environment
leading to survival
Even in extreme conditions such as extreme heat and the absence of water – some thrive by means of their
evolutionary characteristics
Most organisms on earth are found in water
Deep oceans are yet to be studied more
Main source of energy: Sun (Photosynthesis – autotrophs/phototrophs)
Food Chain – series of food chain are called food web (constant flow of energy)
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