Name: What is Physical Geography? Crash Course Geography #4
Uploaded: 2022-06-03T05:33:41.000Z
Duration: 11 min 9 s
Description: Thousands of YouTube videos with English-Chinese subtitles! Now you can learn to understand native speakers, expand your vocabulary, and improve your pronunciation...

When I do fieldwork, I always take photos.

Transition words & phrases

Not only because I love capturing memories (like anyone else), but because they also

serve as an important record of a given moment in history.

Like when I went to Madagascar and took hundreds of photos of erosional formations in the rolling

From those images, we could see how Madagascar's highlands had changed from a once widely forested

area to one where deforestation has resulted in serious gashes and erosional gullies called

With fewer trees, the soil becomes even more vulnerable to these landslide-like events

- setting the stage for even more dramatic changes to come.

It's changed as continents have shifted and humans have interacted with the environment.

Some changes happen slowly -- we'd have to watch for millions of years to see the

continents drift or the Rocky Mountains grow.

But a storm or avalanche changes the landscape in the blink of an eye.

Both types of change have tremendous influence over our lives, from small decisions like

what we'll wear today to bigger choices like where we choose to live.

All of these changes, above and below the Earth's surface, are part of physical geography.

And for the first half of the series, physical geography is the lens we'll use to tell

I'm Alizé Carrère and this is Crash Course Geography.

Up 'til now we've been talking about tools and ideas that apply throughout geography.

But the Earth is a big and complex place.

So traditionally, geography is studied as two interconnected parts: physical geography

Physical geography is all about recognizing the characteristics of the environment and

the processes that create, modify and destroy those environments.

But remember, human-environment interactions are fundamental to studying geography.

So as physical geographers, we'll look for answers to our questions in the processes

that happen without humans and because of humans.

We'll be exploring a particular space: the geo-ecosphere, which is the narrow zone on

Earth's surface that contains all the different landscapes and major systems that interact

By breaking the Earth up into distinct systems, we can look for connections that help us understand

complex problems like climate change or the loss of variety of life in different habitats.

In physical geography, we think of there being four major Earth systems.

First, there's the atmosphere, or the layers of air surrounding Earth that give us clouds,

weather, the ozone layer, and the air we breathe.

Then there's the hydrosphere, or all the water on, below, or above the planet's surface.

So all the water in the soils, under the ground, in oceans, lakes, ice caps, and streams, as

well as in plants, animals, our bodies, and all the water molecules in the atmosphere!

Next we have the lithosphere, which is the rocky outermost layer of Earth.

The rocks of the lithosphere form our continents and line the bottom of Earth's oceans.

And finally, the parts of Earth where life can exist make up the biosphere.

Whether it's a deep, dark, cold spot in the ocean, a barren mountaintop, or a lush, fertile

No matter what we choose to focus on in physical geography, all four spheres will play a role.

Like ecosystems are communities of living things interacting in concert with their nonliving

environment based on these underlying Earth systems.

Off the northeastern coast of what we know as Australia is the world's largest coral

Well actually, it's almost 3000 individual reefs that are home to more than 9000 different

species of tiny, fragile-yet-resilient organisms working together to build their home.

Since the Great Barrier Reef, like all coral reefs, is life, the reef itself is part

Even the skeleton of each reef is built by the coral itself.

The hard corals of the Great Barrier Reef secrete the chemical compound calcium carbonate,

That limestone is part of the lithosphere and forms the rock foundation that protects

the corals and other organisms from the waves.

Even when the coral dies, the limestone remains and becomes a spot for new coral to grow and

The Great Barrier Reef exists in the Pacific Ocean, underwater, so it's surrounded by the

And the atmosphere still interacts with this marine ecosystem through storms!

Believe it or not, these delicate-looking coral reefs are most successful in areas where

the hydrosphere and the atmosphere clash, creating lots of waves.

It's estimated that thousands of cubic kilometers of ocean waters flow through the Great Barrier

Reef each year, bringing food, oxygen, and keeping temperatures moderate for the organisms

Clashes between the atmosphere and hydrosphere can become destructive, though.

All four spheres are involved when the high winds and towering waves brought by Pacific

cyclones destroy softer corals and damage the more hearty corals.

But cyclones bring cooler water into these shallow ecosystems and can clean up the reef

by whisking away sediment that has built up over time.

By looking for interactions between all the Earth systems we can identify what helps the

We'll talk more next episode about how the Earth formed these spheres and how it moves.

For now though, we can start thinking like physical geographers and ask “what causes

The Earth's atmosphere, hydrosphere, lithosphere, and biosphere are driven and influenced by

the Sun and insolation, or incoming solar radiation.

For example, the Sun's energy heats up liquid water, causing it to evaporate into water

That water vapor may condense in the atmosphere, forming clouds and rain.

That rain may enter a river, a lake, or become frozen in a glacier.

Over time, that glacier might move down a mountainside, altering Earth's surface and

providing a habitat for the smallest of bacteria.

As physical geographers, our area of study is everything the light touches -- and more.

So just like you can be a doctor but spend most of your time studying the heart to become

a cardiologist, physical geographers break up the geo-ecosphere and specialize in different

Like what if we visit …Guatemala to look at bananas?

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What is Physical Geography? Crash Course Geography #4

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