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As you go up a mountain, the air becomes less compressed and is therefore thinner.

The important effect of this decrease in pressure is this: in a given volume of air, there are fewer molecules present. This is really just another way of saying that the pressure is lower (this is called Boyle's law). The percentage of those molecules that are oxygen is exactly the same: 21%. The problem is that there are fewer molecules of everything present, including oxygen.

So although the percentage of oxygen in the atmosphere is the same, the thinner air means there is less oxygen to breathe.

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Troposphere
The troposphere contains 75% of the atmosphere's total mass

In either space or time the troposphere is not constant

Weather occurs in the troposphere

The troposphere is 10 miles from the equator

The troposphere is 5-7 miles above the poles

Does not contain ozone

The altitude of the tropopause at the poles is 5 miles

The temperature in the troposphere can reach -80*C

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The atmosphere becomes less dense as altitude increases because there is less weight on the air molecules, making them less compressed. The air at lower altitudes is denser because it is pressed down by the weight of all the air molecules above.

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the outermost region of a planet's atmosphere.

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the outermost region of a planet's atmosphere.

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Muna / suhaila

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~ When altitude increases, air temperature decreases.
~ This is because, with an increase in altitude, there is a decrease in air pressure.
~ When air pressure decreases, air cools down.

~ The density of air molecules is greatest near the surface and thins out as the altitude increases.

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Salama and Maitha (salty paper) question 

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Salama and Maitha (salty paper) question 

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When altitude increases air temperature decreases. This is because with an increase in alti

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You can imagine a column of air, with its bottom at sea level, rising to the top of the atmosphere. At sea level, the air is being compressed by all of the air in the column. That is a lot of weight, about 10,000 kg per square meter on the surface of the Earth. A significant fraction of that is also sitting on top of you, by the way. All that weight, pushes down hard on the air and compresses it. When you compress a gas, it becomes denser.

As you go up in elevation, the air at the bottom of the column goes below you and the column of air above you, pushing down, gets shorter. Moreover, because the densest air is at the bottom, the weight of the column above you decreases rapidly.

For example, Mount Everest is about 8,848 meters above sea level. From the above graph, you can see that the air pressure at that height is less than one third of the pressure at sea level. Therefore, the density of air is also less that one third of the density at sea level. That means every breath draws in less than one third of the oxygen that most people are comfortable with. This is why it is absolutely necessary to wear an oxygen mask when climbing that high:

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When altitude increases air temperature decreases. This is because with an increase in alti

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The atmosphere is divided into five layers. It is thickest near the surface and thins out with height until it eventually merges with space.

1) The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer.
2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.
3) Meteors or rock fragments burn up in the mesosphere.
4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits.
5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.

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Troposphere
The troposphere starts at the Earth's surface and extends 8 to 14.5 kilometers high. This part of the atmosphere is the most dense. Almost all weather is in this region.
Stratosphere
The stratosphere starts just above the troposphere and extends to 50 kilometers high. The ozone layer, which absorbs and scatters the solar ultraviolet radiation, is in this layer.
Mesosphere
The mesosphere starts just above the stratosphere and extends to 85 kilometers high. Meteors burn up in this layer
Thermosphere
The thermosphere starts just above the mesosphere and extends to 600 kilometers high. Aurora and satellites occur in this layer.

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Exosphere
Thermosphere

Maryam ahmed and asma question 3) So although the percentage of oxygen in the atmosphere is the same, the thinner air means there is less oxygen to breathe. Try using our barometric pressure calculator to see how air pressure changes at high altitudes

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) The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer.
2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.
3) Meteors or rock fragments burn up in the mesosphere.
4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits.
5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.

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The atmosphere is comprised of layers based on temperature. These layers are the troposphere, stratosphere, mesosphere and thermosphere. A further region at about 500 km above the Earth's surface is called the exosphere.

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The atmosphere is comprised of layers based on temperature. These layers are the troposphere, stratosphere, mesosphere and thermosphere. A further region at about 500 km above the Earth's surface is called the exosphere.

# data[].attributes.body
Troposphere
The troposphere starts at the Earth's surface and extends 8 to 14.5 kilometers high. This part of the atmosphere is the most dense. Almost all weather is in this region.
Stratosphere
The stratosphere starts just above the troposphere and extends to 50 kilometers high. The ozone layer, which absorbs and scatters the solar ultraviolet radiation, is in this layer.
Mesosphere
The mesosphere starts just above the stratosphere and extends to 85 kilometers high. Meteors burn up in this layer
Thermosphere
The thermosphere starts just above the mesosphere and extends to 600 kilometers high. Aurora and satellites occur in this layer.
Exosphere
This is the upper limit of our atmosphere. It extends from the top of the thermosphere up to 10,000 km.

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

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The atmosphere can be divided into layers based on its temperature, as shown in the figure below. These layers are the troposphere, the stratosphere, the mesosphere and the thermosphere. A further region, beginning about 500 km above the Earth's surface, is called the exosphere.

The red line on the figure below shows how temperature varies with height (the temperature scale is given along the bottom of the diagram). The scale on the right shows the pressure. For example, at a height of 50 km, the pressure is only about one thousandth of the pressure at the ground.

The Troposphere

This is the lowest part of the atmosphere - the part we live in. It contains most of our weather - clouds, rain, snow. In this part of the atmosphere the temperature gets colder as the distance above the earth increases, by about 6.5°C per kilometre. The actual change of temperature with height varies from day to day, depending on the weather.

The troposphere contains about 75% of all of the air in the atmosphere, and almost all of the water vapour (which forms clouds and rain). The decrease in temperature with height is a result of the decreasing pressure. If a parcel of air moves upwards it expands (because of the lower pressure). When air expands it cools. So air higher up is cooler than air lower down.

The lowest part of the troposphere is called the boundary layer. This is where the air motion is determined by the properties of the Earth's surface. Turbulence is generated as the wind blows over the Earth's surface, and by thermals rising from the land as it is heated by the sun. This turbulence redistributes heat and moisture within the boundary layer, as well as pollutants and other constituents of the atmosphere.

The top of the troposphere is called the tropopause. This is lowest at the poles, where it is about 7 - 10 km above the Earth's surface. It is highest (about 17 - 18 km) near the equator.

The Stratosphere

This extends upwards from the tropopause to about 50 km. It contains much of the ozone in the atmosphere. The increase in temperature with height occurs because of absorption of ultraviolet (UV) radiation from the sun by this ozone. Temperatures in the stratosphere are highest over the summer pole, and lowest over the winter pole.

By absorbing dangerous UV radiation, the ozone in the stratosphere protects us from skin cancer and other health damage. However chemicals (called CFCs or freons, and halons) which were once used in refrigerators, spray cans and fire extinguishers have reduced the amount of ozone in the stratosphere, particularly at polar latitudes, leading to the so-called "Antarctic ozone hole".

Now humans have stopped making most of the harmful CFCs we expect the ozone hole will eventually recover over the 21st century, but this is a slow process.

The Mesosphere

The region above the stratosphere is called the mesosphere. Here the temperature again decreases with height, reaching a minimum of about -90°C at the "mesopause".

The Thermosphere and Ionosphere

The thermosphere lies above the mesopause, and is a region in which temperatures again increase with height. This temperature increase is caused by the absorption of energetic ultraviolet and X-Ray radiation from the sun.

The region of the atmosphere above about 80 km is also caused the "ionosphere", since the energetic solar radiation knocks electrons off molecules and atoms, turning them into "ions" with a positive charge. The temperature of the thermosphere varies between night and day and between the seasons, as do the numbers of ions and electrons which are present. The ionosphere reflects and absorbs radio waves, allowing us to receive shortwave radio broadcasts in New Zealand from other parts of the world.

The Exosphere

The region above about 500 km is called the exosphere. It contains mainly oxygen and hydrogen atoms, but there are so few of them that they rarely collide - they follow "ballistic" trajectories under the influence of gravity, and some of them escape right out into space.

The Magnetosphere

The earth behaves like a huge magnet. It traps electrons (negative charge) and protons (positive), concentrating them in two bands about 3,000 and 16,000 km above the globe - the Van Allen "radiation" belts. This outer region surrounding the earth, where charged particles spiral along the magnetic field lines, is called the magnetosphere.

Further information

Visit our Atmosphere National Science Centre

Read about our UV and ozone research

Related links

Our science - atmosphere

UV and ozone

Weather and climate photo gallery

Featured

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Lauder atmospheric research station

NIWA's research station at Lauder in Central Otago specialises in measuring CFCs, ozone, UV levels and greenhouse gases and has a wide range of world-class instruments and research scientists.

technicians_release_a_balloon_at_lauder.png

Technicians release a balloon at Lauder. Chemical sensors attached will measure the vertical ozone profile up to an altitude of around 35 kilometres before descending. [Dave Hansford]

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Layers of the atmosphere. [Credit Bredk. See original]

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# data[].attributes.body
The atmosphere is comprised of layers based on temperature. These layers are the troposphere, stratosphere, mesosphere and thermosphere. A further region at about 500 km above the Earth's surface is called the exosphere.

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💎The atmosphere is comprised of layers based on temperature. These layers are the troposphere, stratosphere, mesosphere and thermosphere. A further region at about 500 km above the Earth's surface is called the exosphere.

💎1) The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer.
💎2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.
💎3) Meteors or rock fragments burn up in the mesosphere.
💎4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits.
💎5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.

Why does temprature change with altitude.
The troposphere is hotter near the Earth’s surface because heat from the Earth warms this air. As the altitude increases the number of air molecules decreases, thus the average of their kinetic energy decreases. The results is a decrease in air temperature with an increase of altitude.

Stratosphere: As the altitude increases, the air temperature increases.

The Stratosphere has a layer of ozone, called the ozone layer. This layer absorbs most of the ultraviolet radiation from sunlight. This results in the stratosphere being warmer.

Mesosphere: As the altitude increases, the air temperature decreases.

The Mesosphere, like the troposphere layer, has a decrease in temperature with altitude because of the decreases in the density of the air molecules.

Thermosphere: As the altitude increases, the air temperature increases.

The Thermosphere is warmed by the absorption of solar X-rays by the nitrogen and oxygen molecules in this outer layer. Thus, the temperature of this layer increases with altitude. .

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The Troposphere
~This is the lowest part of the atmosphere - the part we live in.
~ The troposphere contains about 75% of all of the air in the atmosphere.
The Stratosphere
~This extends upwards from the tropopause to about 50 km.
The Mesosphere
~ The region above the stratosphere.
~ Minimum of about -90°C.
The Thermosphere
~ Is a region in which temperatures again increase with height.
~ This temperature increase is caused by the absorption of energetic ultraviolet and X-Ray radiation from the sun.
The Exosphere
~The atmosphere is comprised of layers based on temperature. These layers are the troposphere, stratosphere, mesosphere and thermosphere. A further region at about 500 km above the Earth's surface is called the exosphere.

# data[].attributes.body
The atmosphere is divided into five layers. It is thickest near the surface and thins out with height until it eventually merges with space.

1) The troposphere is the first layer above the surface and contains half of the Earth's atmosphere. Weather occurs in this layer.
2) Many jet aircrafts fly in the stratosphere because it is very stable. Also, the ozone layer absorbs harmful rays from the Sun.
3) Meteors or rock fragments burn up in the mesosphere.
4) The thermosphere is a layer with auroras. It is also where the space shuttle orbits.
5) The atmosphere merges into space in the extremely thin exosphere. This is the upper limit of our atmosphere.

# data[].attributes.body
The atmosphere has five different layers that are determined by the changes in temperature that happen with increasing altitude.

Troposphere. ...

Stratosphere. ...

Mesosphere. ...

Thermosphere. ...

Exosphere.