Earth’s Life Support Systems

Questions for Today:

• What are the four major components of Earth’s Life Support?

• How do scientist classify Land and Water?

• What are the three factors that sustain life?

• What happens to solar energy reaching the Earth?

The Four Spheres

• Earth’s life support systems are composed of four spherical systems:– Atmosphere– Hydrosphere– Geosphere– Biosphere

The Four Spheres

• Atmosphere– A thin spherical envelope of gases that

surround the Earth’s surface.– Five sections:

• Troposphere*• Stratosphere*• Mesosphere• Thermosphere• Exosphere

The Four Sphere

• Troposphere– Extends from the surface of the earth to as

high as 17 km above sea level.– Contains the majority of the air we breathe.– Consists mostly of:

• Nitrogen (78%)• Oxygen (21%)

– The remaining one percent are composed of greenhouse gases.

• Water Vapor, Carbon Dioxide, and Methane.

The Four Spheres

• Stratosphere– Right above the Troposphere– Extend from the surface 17-50 km.

– Contains the ozone layer (O3)• Ozone filters out the UV rays from the sun• Without Ozone layer, life would start to deteriorate

The Four Spheres

• Hydrosphere– Consists of all water on or near the Earth’s

Surface– Covers 71-73% of the earth’s surface

• Geosphere– The Solid Earth– Core, Mantle, and Crust

• Biosphere– All the living aspects of the Earth– Extends 9 kilometers from the surface.

Fig. 3-6, p. 55

Rock

AtmosphereVegetationand animals

Lithosphere

Biosphere

Mantle

Crust

Soil

Biosphere(living organisms)

Geosphere(crust, mantle, core)

Mantle

Core

Hydrosphere(water)

Crust(soil and rock)

Atmosphere(air)

Life Exists on Land and in Water

• Biomes are large regions on the terrestrial earth with distinct climates and certain species adapted to them.

• Aquatic life zones are how scientist classify the water on Earth– Freshwater (2%)– Marine/Ocean (71%)

Fig. 3-7, p. 55

Average annual precipitation

100–125 cm (40–50 in.)75–100 cm (30–40 in.)50–75 cm (20–30 in.)25–50 cm (10–20 in.)below 25 cm (0–10 in.)

AppalachianMountains

Coastal mountainranges

Sierra Nevada

Great American

Desert

RockyMountains

GreatPlains

MississippiRiver Valley

Deciduous forestCoastal chaparraland scrub

Coniferous forest Desert Coniferous forest Prairie grassland

San Francisco

BaltimoreDenver

St. Louis

Life Sustaining Factors

• Life on Earth Depends on Three major Factors:1.The one way flow of high quality energy

2.The cycling of matter or nutrients through parts of the biosphere.

3.Gravity

What happens to Solar Energy Reaching the Earth

1. The energy reaches earth in the form of EM waves.

• Visible Light, UV, Infrared• Most of this energy is absorbed by the stratosphere

or reflected back into space• Only 5% makes it to the surface.

2. The energy that reaches the earth, warms the air, evaporates and cycles water.

• 1% generates wind• <0.1% is used in photosynthesis

What happens to Solar Energy reaching the Earth

3. 4% of the Sun’s energy is trapped within the ozone layer.

• This causes greenhouse gases to vibrate and release infrared radiation.

• The vibrating gas had high kinetic energy which warms the lower atmosphere and the surface of the earth

• Natural Greenhouse effect.

What Happens to Solar Energy reaching the Earth

• Human Activities, such as burning fossil fuels, increase the amount of greenhouse gases in our upper atmosphere.

• Studies have shown that these activities are increasing the natural greenhouse effect and warming the earth’s atmosphere.

Fig. 3-8, p. 56

Lower Stratosphere(ozone layer)

Solarradiation

UV radiation

Visiblelight Heat radiated

by the earth

Mostabsorbedby ozone

Absorbedby the earth

Greenhouseeffect

Reflected byatmosphere Radiated by

atmosphereas heat

Heat

Troposphere