Earth Science CET (Earth's Major Spheres)

Earth's four major spheres are:

1. Biosphere

2. Atmosphere

3. Hydrosphere

4. Geosphere

These includes all living organisms on Earth and the

ecosystems they form.

It encompasses all life forms, from the smallest bacteria to

the largest mammals, as well as plants, fungi, and

microorganisms.

Biosphere

It is crucial for supporting life, cycling nutrients,

and maintaining ecological balance. It interacts with other

spheres through processes like photosynthesis, respiration,

and decomposition.

Biosphere

The biosphere is known to exist for _______. It is

where life evolved from single-celled prokaryotes to the

complex multicellular organisms found today.

3.5 billion years

The three main components that make up the biosphere are:

1. Lithosphere (Earth’s Crust)

2. Hydrosphere (Water)

3. Atmosphere (Air)

This encompasses all of Earth's water, in

various forms and locations.

It includes oceans, rivers, lakes, glaciers, groundwater, and

water vapor in the atmosphere.

Hydrosphere

This is essential for all known forms of life,

regulates Earth's temperature, shapes landforms through

erosion and sediment deposition, and drives the water cycle,

which distributes heat and moisture around the planet.

Hydrosphere

Steps of Water Cycle:

1. Evaporation

2. Transpiration

3. Condensation

4. Precipitation

5. Runoff

6. Infiltration

7. Groundwater Flow

Water from the Earth’s surface (such as oceans, lakes, and rivers) turns into water vapor due to solar energy. This vapor rises into the atmosphere

Evaporation

Plants release water vapor through tiny pores

(stomata) in their leaves. This process contributes to the

overall water vapor content in the atmosphere.

Transpiration

Water vapor cools and condenses into

clouds. These clouds are formed when water droplets or ice

crystals cluster together.

Condensation

When the condensed water droplets become

heavy enough, they fall back to the Earth as rain, snow,

sleet, or hail.

Precipitation

Precipitation flows over the land, collecting in rivers,

streams, and eventually reaching the oceans.

Runoff

Some precipitation seeps into the ground,

replenishing groundwater.

Infiltration

Underground, water moves within

aquifers, contributing to the overall water cycle.

Groundwater Flow

This refers to the solid parts of the Earth,

including the crust, mantle, and core.

It includes rocks, minerals, soils, and sediments. It is divided

into three layers: the crust (outermost layer), the mantle, (middle layer), and the core (innermost layer).

Geosphere

This provides the foundation for terrestrial

ecosystems, supplies essential minerals and nutrients, and is

involved in tectonic activity, which shapes the Earth's

surface through processes like earthquakes and volcanic

eruptions.

Geosphere

Parts of Geosphere:

1. Crust

2. Upper Mantle

3. Mantle

4. Outer Core

5. Inner Core

The layer we live on, the ____ is the thinnest and least

dense layer of the solid earth.

Crust

How deep are the light rock materials in the earth’s crust?

2 miles to 75 miles deep

The crust contains what elements?

Silicon, Aluminium, and Calcium

Two Types of Crust:

1. Oceanic Crust

2. Continental Crust

The crust of the earth is broken into many pieces called

____ on which the continents and oceans rest.

Plates

It is the crust in the ocean’s floor.

Oceanic Crust

It is the crust that makes up the continent.

Continental Crust

What is the mantle?

1. The largest and thickest layer of the earth.

2. Consists of about 80% of the earth’s mass.

3. It is a very hot surface at about 900°C.

4. This layer is composed of very hot dense rock (ferro-

magnesium silicate rocks) that flows like asphalt under a

heavy weight.

The hot material (magma) in the mantle rises to the top of the

mantle, cools, then sinks, reheats, and rises again. It causes changes in the earth’s surface.

Convection Currents

It is the densest layer of the internal structure of the

earth.

About 3,500 thick from the center.

Made up of heavy metals like iron + oxygen, silicon, and

nickel alloy.

Core

Parts of the Core:

1. Outer Core

2. Inner Core

It is the only layer of the earth

that is liquid. Located below the mantle and is about 1,400

miles thick. It is composed of the melted metals nickel and

iron.

Outer Core

It is the solid center of the

planet. It is composed mostly of iron. The inner core of the

earth has temperatures and pressures so great that the

metals are squeezed together and are not able to move

about like a liquid but are forced to vibrate in place like a

solid.

Inner Core

Boundaries between the layers of the earth:

1. Lithosphere

2. Asthenosphere

3. Mohorovicic Discontinuity

4. Gutenberg Discontinuity

The solid outer section of the earth. It is made

up of the crust as well as the upper layer of the mantle.

Lithosphere

It is a part of the uppermantle that flows like

hot asphalt under heavy weight. Lithospheric plates float

and move around here.

Asthenosphere

It is also known as moho, it is the

interface between crust and mantle.

Mohorovicic Discontinuity

This marks the boundary between the

mantle and the outer core.

Gutenberg Discontinuity

This is the layer of gases surrounding the Earth,

held in place by gravity.

It is composed primarily of nitrogen (78%), oxygen (21%),

and trace gases such as argon, carbon dioxide, and water

vapor.

Atmosphere

The atmosphere protects life on Earth by:

1. Absorbing ultraviolet solar radiation

2. Reducing temperature extremes between day and night

3. Containing the air that organisms breathe.

4. Plays a key role in weather and climate systems

Layers of the Atmosphere:

Exosphere

Thermosphere

Mesosphere

Stratosphere

Troposhere

Extends from the Earth's surface up to about 20 kilometers

(12 miles), varying with latitude and season (thicker at the

equator and thinner at the poles).

Its temperature decreases with altitude, with the average

rate of temperature decrease known as the environmental

lapse rate (about 6.5°C per kilometer).

Contains about 75% of the atmosphere's mass and the

majority of its water vapor and aerosols.

Troposhere

Weather phenomena such as clouds, rain, and storms occur

in this layer.

The lower boundary, the Earth's surface, influences the

temperature and humidity of the air.

Troposhere

It is the boundary between the troposphere

and the stratosphere, where the temperature stops

decreasing with height.

Tropopause

Ranges from about 20 kilometers (12 miles) to approximately

50 kilometers (31 miles) above the Earth's surface.

Its temperature increases with altitude due to the absorption

of ultraviolet (UV) radiation by the ozone layer.

Contains the ozone layer, which absorbs and scatters UV

radiation, protecting living organisms from harmful effects.

Air is more stable and less turbulent compared to the

troposphere, making it favorable for commercial jet aircraft.

Stratosphere

It is the boundary between the stratosphere

and the mesosphere, marked by a transition where

temperature stops increasing.

Stratopause

Extends from about 50 kilometers (31 miles) to around 85

kilometers (53 miles) above the Earth's surface.

Its temperature decreases with altitude, making it the

coldest layer of the atmosphere, with temperatures dropping

to as low as -90°C (-130°F) near the mesopause.

Contains very low air pressure and density.

Meteors entering the Earth's atmosphere burn up in this

layer, creating meteor trails.

Mesosphere

It is the boundary between the mesosphere

and the thermosphere, where the temperature stops

decreasing.

Mesopause

Ranges from about 85 kilometers (53 miles) to between 500

and 1,000 kilometers (311 to 621 miles) above the Earth's

surface.

The temperature increases significantly with altitude,

potentially reaching up to 2,500°C (4,500°F) or higher,

though the high temperature does not translate to a feeling

of heat due to the low density of air molecules.

Contains a small fraction of the atmosphere's mass but is

highly ionized due to solar radiation.

Satellites orbit in the lower thermosphere, and the

International Space Station operates within this layer.

Thermosphere

The thermosphere is home to the region of charged particles that plays a crucial role in radio communication and auroras, what is this region?

Ionosphere

It is the upper boundary of the

thermosphere, transitioning into the exosphere.

Thermopause

It contains a high concentration of ions and free

electrons; affects radio wave propagation and is essential

for long-distance communication and GPS systems; creates

auroras, known as the Northern and Southern Lights,

through interactions with solar wind and the Earth's

magnetic field.

Ionosphere

Extends from the thermopause up to about 10,000

kilometers (6,200 miles) above the Earth's surface,

gradually thinning out into outer space.

Its temperature can vary greatly, and while temperatures

can be very high, the sparse distribution of particles means

that they rarely collide.

Composed of extremely low densities of hydrogen, helium,

and other light gases.

The region where atmospheric particles escape into space.

Contains artificial satellites in high orbits and serves as the

interface between Earth's atmosphere and outer space.

Exosphere