Layers of Atmosphere- Structure and Composition

Layers of Atmosphere: The atmosphere around Earth has layers, each with its characteristics. Earth’s atmosphere is split into four layers: troposphere, stratosphere, mesosphere, and thermosphere. These layers are separated because of how hot or cold they are. The lower layers are where weather happens, like rain and wind, while cool things like the pretty aurora occur in the higher layers. If we know how the temperature changes as we go up, we can understand how the air around us behaves. In this article, we will learn about the different layers of the atmosphere around the Earth.

Let’s get started!

Layers of Atmosphere

What Is Atmosphere?

The air around Earth is called the atmosphere. It’s like a cosy blanket made of gases that wrap around our planet. Gravity is what keeps this atmospheric blanket close to Earth.

The main ingredients in this air blanket are argon, oxygen, and nitrogen. They make up most of what’s in the atmosphere.

Let’s break down some key points about the atmosphere:

Definition

“Atmosphere is a protective layer of gases that shelters all life on Earth, keeping temperatures within a relatively small range and blocking out harmful rays of sunlight.”

Features of the Atmosphere:

• It holds onto the sun’s warmth, so it doesn’t escape into space.
• It shields living things from the sun’s harmful rays.
• The atmosphere is a big player in Earth’s water cycle.
• It helps maintain a comfortable climate on Earth.

Boundary with Outer Space: Unlike a solid boundary, there’s no clear line between the atmosphere and outer space. It gradually becomes less and less dense until it kind of blends into outer space.

Layers of Atmosphere

The air around us is divided into five layers, and these layers are set by how the temperature changes as you go higher up. Here are the layers:

1. Exosphere
2. Thermosphere
3. Mesosphere
4. Stratosphere
5. Troposphere

Summary of Layers of Atmosphere

Summary of Layers of Atmosphere
Region	Altitude Range (km)	Temperature Range(0oC)	Important Characteristics
Troposphere	0-11	15 to -56	Weather occurs here
Stratosphere	11-50	-56 to -2	The ozone layer is present here
Mesosphere	50-85	-2 to -92	Meteors burn in this layer
Thermosphere	85-800	-92 to 1200	Auroras occur here

Structure of the Atmosphere

When you go higher up in the atmosphere, things change. The pressure and how tightly packed the air is (density) usually decrease, but temperature doesn’t follow a steady pattern. The way temperature changes over a distance is called a temperature gradient.

The Earth’s atmosphere is split into layers, and we decide these layers based on how the temperature changes. The heat source in each layer decides how much the temperature changes. So, the temperature gradient is a bit like the atmosphere’s way of dealing with heat at different heights.

Troposphere

Even though sunlight comes from above, the bottom part of the troposphere, which is the closest layer to the Earth’s surface, gets heated up the most. This is because the Earth’s surface is really good at soaking in various types of sunlight.

When warm air goes up, it spreads out. And when air spreads out, it cools down. That’s why the lower part of the troposphere, near the Earth’s surface, is warmer. The air on the Earth’s surface soaks up the sun’s energy, warms up, and then rises. As it rises, it cools down. That’s how the troposphere works – warm at the bottom and cooler as you go up.

Stratosphere

Above the troposphere is the stratosphere, reaching up to 50 kilometers high. Unlike the layer below it, the stratosphere doesn’t have clouds or any weather events. That’s why airplanes prefer flying in the stratosphere for a comfortable journey.

One very important thing in the stratosphere is the ozone layer. This special layer shields us from the sun’s harmful rays. So, not only is the stratosphere great for smooth plane rides, but it also acts like a protective umbrella against the sun’s not-so-friendly effects.

Mesosphere

As you go higher in the mesosphere, things get colder. The reason is, there aren’t many gas molecules in the mesosphere to soak up the Sun’s warmth. The only source of heat here is from the layer below, the stratosphere. The mesosphere can be super chilly, especially at the highest point, reaching temperatures as low as -90°C. It’s like a really cold zone up there!

Thermosphere

Up in the thermosphere, the molecules are spread out a lot – there aren’t many packed together. In fact, a single gas molecule can travel about 1 km without bumping into another one. Because there are so few collisions between molecules, there’s not much warmth transferred, and it feels really cold up there.

In the upper part of the thermosphere, you’ll find satellites orbiting around. It’s like a chilly space neighborhood where these satellites hang out.

Ionosphere

Inside the thermosphere, there’s a special zone called the ionosphere. It got its name because of solar radiation that makes gas molecules turn into positively charged ions and negatively charged electrons. These free electrons move around in the ionosphere, creating electric currents.

Because of these free ions, the ionosphere has some cool features. One of them is the aurora, those amazing lights we see in the sky, known as the Northern Lights and Southern Lights. These lights happen right there in the Earth’s ionosphere.

Exosphere

The exosphere is like the last part of Earth’s gas layer. But here’s the interesting part: there’s no clear line saying where Earth’s atmosphere ends and outer space begins. The air in the exosphere is slowly escaping, kind of leaking out, into outer space. It’s like the final frontier where Earth’s air meets the vastness of space.

Composition of Atmosphere – Gases in the Atmosphere

The composition of our atmosphere is as follows:

Composition of Atmosphere
Nitrogen	78.08%
Oxygen	20.95%
Argon	0.93%
Carbon Dioxide	0.038%

Dry air from earth’s atmosphere contains 0.038% of carbon dioxide, 20.95% of oxygen, 78.08% of nitrogen and 0.93% of argon.

What Would Happen if the Earth’s Atmosphere Disappeared?

If the Earth’s atmosphere disappeared, the following things would occur:

1. Without the air, birds and planes wouldn’t stay up in the sky. Even though we can’t see it, air has weight that supports flying things.
2. The blue sky we see is because of our atmosphere. If there’s no atmosphere, the sky would turn black. The gases and particles in the air scatter sunlight, making it look blue.
3. No air means no sound. Even if you felt vibrations, there wouldn’t be any noise. Sound needs something, like air, to travel through.
4. All the water in rivers, lakes, and oceans would boil away. Boiling happens when the pressure on a liquid is less than its vapor pressure. In a vacuum (no air), water boils easily.
5. Creatures that rely on air, like us, would struggle. Breathing is impossible without air, so organisms that need it would die.

It’s a reminder of how important our invisible atmosphere is for everything around us!

Trick to Remember the Layers of the Atmosphere

Mnemonic device for the layers of the atmosphere:

That Snake Must Think: I’m Evil

The first alphabet of each word corresponds to the layer of Earth’s atmosphere starting from the Earth’s surface. These are troposphere, stratosphere, mesosphere, thermosphere. The thermosphere is divided into the ionosphere (northern lights) and exosphere (satellites).

Conclusion

Every layer in Earth’s air has its own special role. The troposphere is where weather happens, the stratosphere acts like a protective shield, the mesosphere is super cold, the thermosphere is like a space area, and the exosphere kind of mixes with outer space. Understanding these layers shows us how they team up to make Earth a unique and cozy spot in the vast universe. Each layer has a job, like shaping the weather and keeping us secure, making our planet just perfect for living!

FAQs on Layers of Atmosphere

Why is the Troposphere Warmer At The Base?

Sunlight reaches Earth’s surface top-down, but the troposphere gets heated mainly at the bottom. The Earth absorbs solar radiation better than the air, so when warm air rises, it expands and cools, making the lower troposphere warmer as surface air absorbs sunlight, heats up, and moves upward, cooling down.

Why is Stratosphere warmer than the troposphere?

In the stratosphere, ozone molecules absorb strong ultraviolet sunlight, turning it into heat. Unlike the troposphere, this makes the stratosphere warmer as you move higher up.

Why would an unprotected astronaut’s blood boil in the mesosphere?

If an astronaut passes through the mesosphere, they could suffer severe burns from the sun’s ultraviolet light since the protective ozone layer, which shields from UV rays, is in the stratosphere below. Additionally, meteorites entering the atmosphere from outer space burn up in this layer.

Which is the coldest layer of the atmosphere?

The mesosphere is the coldest layer of the atmosphere.

In which layer of the atmosphere do planes fly?

Planes fly in the stratosphere for a smooth ride due to less turbulence.