What are the four layers of the atmosphere

These 4 layers each have unique characteristics to each one of them. In this lesson, we will learn these layers one by one.

Distance: "The troposphere starts at Earth's surface and goes up to a height of 7 to 20 km (4 to 12 miles, or 23,000 to 65,000 feet) above sea level"[1]

A photo of the Troposphere

This layer is the lowest layer of the Earth, the troposphere (trop-os-feer). This layer is where we, the humans, live in (and all the weather is at!). This layer contains nearly 90% of the atmosphere's total mass! Almost all of the Earth's water vapor, carbon dioxide, air pollution, clouds, weather and life forms live in. The word, "troposphere", literally means "change/turning ball", as the gases turn and mix in this layer. These gases mix due to the differences in air temperature and density.

Distance: "The bottom of the stratosphere is around 10 km (6.2 miles or about 33,000 feet) above the ground at middle latitudes. The top of the stratosphere occurs at an altitude of 50 km (31 miles)"[2]

The layer above the Troposphere is known as the Stratosphere (strat-os-feer). Gases in the stratosphere are layered (why it has the prefix, "strato", meaning layered), the air is very thin (little moisture as well), and is extremely cold (lower stratosphere). Although the lower part of the stratosphere is cold, the heat in the stratosphere increases as altitude increases. This is because of the ozone layer in the upper part of the Stratosphere. The Ozone layer absorbs ultraviolet radiation from the sun, and as a result, warms up the air. This ozone layer is key to our safe living on Earth.

Distance: "The mesosphere starts at 50 km (31 miles) above Earth's surface and goes up to 85 km (53 miles) high"[3]

Above the Stratosphere is the Mesosphere (mez-os-feer), the middle layer of the atmosphere (meso- meaning "middle"). This layer is the coldest layer (temperature decreases as altitude increases). Temperatures can be as low as -93 degrees Celsius at the top of the Mesosphere.

Distance: "It extends from about 90 km (56 miles) to between 500 and 1,000 km (311 to 621 miles) above our planet"[4]

The thermosphere is included in this picture.

The uppermost atmosphere is called the Thermosphere (therm-os-feer). Here, the temperature again increases with altitude. This is because atoms of nitrogen and oxygen absorb high-energy solar radiation and give off thermal energy... this causes the temperature to increase up to 1,000 degrees Celsius.

Even though it may seem, it is actually not hot in the Thermosphere. Pay close attention to these details:

• Temperature is different from heat
  • Temperature is the measure of the average energy of particles in motion. Thus, the thermosphere has particles moving very fast.
  • Heat is the transfer of thermal energy between objects of different temperatures. Therefore, particles must touch one and another to transfer heat.

In the Thermosphere, it is has a low density--thus the particles in the Thermosphere usually don't collide, thus not giving off heat.

The Earth’s atmosphere is divided into four layers or ‘spheres’. Each layer is characterized by a different gradient of the temperature as a function of altitude.

Troposphere

The troposphere (between 0 and about 15 kilometers) is the first layer above the Earth’s surface and contains approximately 85 to 90 % of the mass of the Earth’s atmosphere. It is characterized by decreasing temperature with increasing altitude.

The troposphere’s thermal profile is largely the result of the heating of the Earth’s surface by incoming solar radiation. Heat is then transferred up through the troposphere by a combination of convective and turbulent transfer. Weather occurs in the Earth’s troposphere.

Stratosphere

In the stratosphere (between approximately 15 and 50 km) the temperature rises as a function of increasing height.

This warming is the result of the direct absorption of solar radiation by the ozone layer, thereby preventing a large part of harmful ultraviolet radiation from the sun to reach the Earth’s surface.

Mesosphere

The mesosphere is the next layer of the atmosphere (from 50 to 90 km), characterized by temperatures that decrease the further up one goes to an average of -90°C.

A lot of meteors burn up in this layer while entering the Earth’s atmosphere.

Thermosphere

Thereafter the thermosphere takes over where temperatures increases steadily with altitude. It is the layer of the atmosphere which is first exposed to the Sun’s radiation.

The thermosphere also includes the ionosphere, a region of the atmosphere that is filled with charged particles, where especially the auroras occur.

Earth's atmosphere has a series of layers, each with its own specific traits. Moving upward from ground level, these layers are called the troposphere, stratosphere, mesosphere, thermosphere, and exosphere. The exosphere gradually fades away into the realm of interplanetary space.

Layers of the atmosphere: troposphere, stratosphere, mesosphere and thermosphere.

UCAR/Randy Russell

Troposphere

The troposphere is the lowest layer of our atmosphere. Starting at ground level, it extends upward to about 10 km (6.2 miles or about 33,000 feet) above sea level. We humans live in the troposphere, and nearly all weather occurs in this lowest layer. Most clouds appear here, mainly because 99% of the water vapor in the atmosphere is found in the troposphere. Air pressure drops, and temperatures get colder, as you climb higher in the troposphere.

Stratosphere

The next layer up is called the stratosphere. The stratosphere extends from the top of the troposphere to about 50 km (31 miles) above the ground. The infamous ozone layer is found within the stratosphere. Ozone molecules in this layer absorb high-energy ultraviolet (UV) light from the Sun, converting the UV energy into heat. Unlike the troposphere, the stratosphere actually gets warmer the higher you go! That trend of rising temperatures with altitude means that air in the stratosphere lacks the turbulence and updrafts of the troposphere beneath. Commercial passenger jets fly in the lower stratosphere, partly because this less-turbulent layer provides a smoother ride. The jet stream flows near the border between the troposphere and the stratosphere.

Mesosphere

Above the stratosphere is the mesosphere. It extends upward to a height of about 85 km (53 miles) above our planet. Most meteors burn up in the mesosphere. Unlike the stratosphere, temperatures once again grow colder as you rise up through the mesosphere. The coldest temperatures in Earth's atmosphere, about -90° C (-130° F), are found near the top of this layer. The air in the mesosphere is far too thin to breathe (the air pressure at the bottom of the layer is well below 1% of the pressure at sea level and continues dropping as you go higher).

Thermosphere

The layer of very rare air above the mesosphere is called the thermosphere. High-energy X-rays and UV radiation from the Sun are absorbed in the thermosphere, raising its temperature to hundreds or at times thousands of degrees. However, the air in this layer is so thin that it would feel freezing cold to us! In many ways, the thermosphere is more like outer space than a part of the atmosphere. Many satellites actually orbit Earth within the thermosphere! Variations in the amount of energy coming from the Sun exert a powerful influence on both the height of the top of this layer and the temperature within it. Because of this, the top of the thermosphere can be found anywhere between 500 and 1,000 km (311 to 621 miles) above the ground. Temperatures in the upper thermosphere can range from about 500° C (932° F) to 2,000° C (3,632° F) or higher. The aurora, the Northern Lights and Southern Lights, occur in the thermosphere.

Exosphere

Although some experts consider the thermosphere to be the uppermost layer of our atmosphere, others consider the exosphere to be the actual "final frontier" of Earth's gaseous envelope. As you might imagine, the "air" in the exosphere is very, very, very thin, making this layer even more space-like than the thermosphere. In fact, the air in the exosphere is constantly - though very gradually - "leaking" out of Earth's atmosphere into outer space. There is no clear-cut upper boundary where the exosphere finally fades away into space. Different definitions place the top of the exosphere somewhere between 100,000 km (62,000 miles) and 190,000 km (120,000 miles) above the surface of Earth. The latter value is about halfway to the Moon!

Ionosphere

The ionosphere is not a distinct layer like the others mentioned above. Instead, the ionosphere is a series of regions in parts of the mesosphere and thermosphere where high-energy radiation from the Sun has knocked electrons loose from their parent atoms and molecules. The electrically charged atoms and molecules that are formed in this way are called ions, giving the ionosphere its name and endowing this region with some special properties.

What are the 4 layers of the atmosphere and their unique characteristics?

Why is the atmosphere divided into 4 layers?