Hello, fellow Earth scientists! Bea here. Today we're going to be exploring the systems that make
up our planet: the Earth's spheres. Every habitat, biome, and landscape on Earth
is a delicate balance between many different pieces, like the water and sea life in a
coral reef or the jagged rocks and cold weather atop a mountain. Changing just one
of these pieces can have a huge impact on everything involved in that balancing act.
For example, imagine a beach, cool waves splashing on the powdery sand,
seagulls flying on warm breezes, and schools of fish darting through the seaweed. Now
imagine changing any of the pieces of this delicate system.
What would happen? Well, imagine that the plants and animals in the ocean suddenly
disappeared. Without the gases they produce, the very air we breathe would be different.
If the air was different, those warm, beachy breezes might be replaced with blizzards or
scorching droughts. If the weather was different, the ocean itself would change
and maybe even evaporate away. And without the ocean's waves to crush up corals, rocks,
and shells, there'd be no sand. Would any of that even still qualify as a beach?
As you can tell, all of the parts in this system are closely related. Changing one
will result in changes to all of the others that can span the entire world.
These different components are part of systems called the Earth's spheres that work together
to make up every single thing on our planet. By the end of this lesson, you'll be able to
explain what the Earth's four spheres are, explain why the Earth's spheres are each important parts
of the Earth system, and explain how the Earth's spheres interact. Let's get started!
From the deepest movements in the planet's core to the formation of weather miles above the ground,
the Earth is home to millions of connected processes. Together,
we call them the Earth system. The Earth system is all of the natural processes that happen
and interact on Earth. But think back to the beach example. Although the sand, water,
winds, and sea life were all connected, do you think they're influenced by the same processes?
The different parts of a beach are representative of different parts within the Earth system,
and each is shaped by its own unique set of processes. The Earth system
is made of four smaller systems called spheres that are each distinct but connected:
the atmosphere, the hydrosphere, the geosphere, and the biosphere.
These four systems work together to form the entirety of the Earth system.
The first sphere we'll take a closer look at is
the atmosphere. The first part of the word atmosphere is the prefix "atmo,"
which means vapor or gas. So with this in mind, pause the video here,
and take a moment to jot down your predictions about what might be part of this system.
The atmosphere is the system that contains all of Earth's air. The air in Earth's atmosphere is
made of a mix of different gases, including nitrogen, oxygen, carbon dioxide, and water
vapor. So, you can probably already tell how the atmosphere is closely linked to all life on Earth,
since we need air to live. Supporting life isn't the only job of the atmosphere though. This
layer of gases also keeps the conditions on our planet stable by regulating the temperature and
deflecting radiation from space. The atmosphere is also where Earth's weather patterns form.
From a gentle breeze to a raging hurricane, the atmosphere is home to it all.
The hydrosphere's name contains the prefix "hydro," which means water,
so the hydrosphere contains... you guessed it! All the water on Earth.
This includes the salt water in the oceans and seas as well as fresh water in rivers
and lakes and frozen in glaciers. It even includes the water stored in
deep underground reservoirs and the water vapor in clouds. The hydrosphere is truly a huge system.
About three-quarters of our planet's surface is covered in water, and that doesn't even include
the water above and below the ground. The presence of a hydrosphere is part of what makes Earth
unique and what makes it able to support life. The hydrosphere has impacts on every other sphere
within the Earth system too. For example, as water moves around the planet in ocean currents,
it can affect weather patterns, like global temperatures and rainfall.
Next up is the geosphere. The prefix "geo" means Earth. So, what do you think the geosphere is? It
includes all the rocks and minerals on Earth's surface and below. That means all of the land
on every continent and island is part of the geosphere. So is the sea floor and the even
deeper layers of molten metal below the Earth's crust. Like the other spheres, the geosphere is
constantly changing as it's shaped by a variety of different processes. Huge segments of the Earth's
crust are constantly shifting rearranging the continents themselves, inch by inch.
Volcanoes are erupting and slowly creating new mountain ranges,
and deep within the Earth's mantle and outer core, molten rock is flowing,
influencing this volcanic activity. But as we know by now, the geosphere is part of a larger system,
so it's also impacted by the other spheres. Strong winds in the atmosphere wear mountains
down into dust over millions of years. Similarly, the constant crashing of waves in the hydrosphere
breaks rocks from the seafloor apart into sand. Processes in all of Earth's other
spheres have shaped the geosphere into the world we call home today.
So, we've talked about the atmosphere, hydrosphere, and geosphere. Air, water,
and rocks cover just about everything on Earth's surface, right? Wait, what about us!
Humans are part of the fourth and final sphere: the biosphere. The prefix "bio" means life,
so the biosphere includes all living things. That means everything from birds flying miles above
the ground, to bizarre fish at the bottom of the sea, to humans walking through cities together.
We're all part of the biosphere. So are towering trees, forests of seaweed,
bioluminescent mushrooms, and blooming flowers. In fact, so are the tiny single-celled bacteria
and other microorganisms that live in the soil beneath these plants' roots.
If it's on Earth and it's alive, it's part of the biosphere.
Of course, the biosphere interacts with every other sphere in many unique ways.
Think about a forest full of trees. They bury their roots deep within soil
containing dirt from the geosphere. They take in water from the hydrosphere when it rains.
Then they absorb carbon dioxide from the atmosphere and release oxygen into it. Trees are
just one example of how the biosphere is connected to all of the other spheres in the Earth system.
Can you think of another way the biosphere interacts with a different sphere, like the
atmosphere or hydrosphere? Pause the video here, and write down your thoughts in your guided notes.
Every living thing in the biosphere needs the air from the atmosphere, the water from the
hydrosphere, and the rocks from the geosphere to survive. And at the same time, those other spheres
rely on each other too. All of these spheres are closely interconnected. Together, they form
the Earth system, a system that we don't just need but that we're also an essential part of.
So let's recap what we've learned today. You now know that the Earth system is the system of
all the natural processes happening on Earth. The Earth system contains the atmosphere, hydrosphere,
geosphere, and biosphere. Each of Earth's spheres plays an essential role in shaping our planet, and
all of the different spheres are closely interconnected. Be sure to check out the
engaging practice games and thought-provoking PDF extension activities that go with this lesson.
They'll help you get ready for our next lesson, where we'll explore some of the cycles that happen
within these spheres. And remember, in Earth science as in life, you rock! See you next time!