The Earth's atmosphere

Monitoring the atmosphere

The Earth’s atmosphere is a thin blanket of gases (nitrogen 78%, oxygen 21%, and other trace gases 1%) that surrounds the planet. Without the atmosphere, the Earth would be lifeless.

The atmosphere regulates the Earth’s temperature and protects living things from the Sun’s most harmful rays. All weather takes place in the atmosphere, most of it in the lower atmosphere.

Europe’s Meteosat and Metop weather satellites keep an eye on the atmosphere, monitoring air quality and pollutants, ozone, trace and greenhouse gases, fires, and aerosols (such as volcanic ash and Saharan dust).

About the atmosphere

The Earth’s atmosphere is generally divided into four layers based on temperature: troposphere, stratosphere, mesosphere and thermosphere. In some layers the temperature increases with altitude, while in others it decreases.

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Troposphere

The thickness of the troposphere varies around the planet and extends from the Earth’s surface to a height of around 16km at the equator, to as little as 8km at the poles
The thickness of the troposphere also varies with the seasons – it is thicker in the summer and thinner in the winter around the planet
The Earth’s weather occurs in the troposphere
The temperature generally drops with height at an average rate of 6.5° Celsius/km

Stratosphere

The second layer of the Earth’s atmosphere, extending to about 12-50km
The border between the stratosphere and the troposphere below is called the tropopause
This layer is heated by the absorption of the sun’s incoming ultraviolet radiation by ozone
The ozone layer is found within the stratosphere at between 15-30km

Mesosphere

The mesosphere is a layer of the Earth’s atmosphere, located 50–85km from the Earth's surface
This layer absorbs very little of the sun’s rays and the temperature at the top of this layer can be as low as -90° Celsius
Most meteors from space burn up in this layer, where you'll also find special 'noctilucent' clouds and strange types of lightning called 'sprites' and 'elves'

Thermosphere

The thermosphere is located directly above the mesosphere and extends from around 90km to 500-1000km above the Earth
The sun strongly influences the temperature in the thermosphere and temperatures in the upper regions can range from 500-2000° Celsius

Skydive from the Stratosphere

On 14 October 2012, Austrian Skydiver, Felix Baumgartner, broke the world record for the highest ever skydive, jumping from a specially modified helium balloon, 39km above the Earth in the stratosphere. On the way down he also broke the sound barrier reaching an estimated speed of 1358 km/h. View a profile of Felix's fall through the atmosphere.

Monitoring Air Quality

Air quality is defined as the quality of the air that we breathe directly at the surface. When air quality is poor, due for instance to industrial pollutants, it affects the day-to-day lives of Europe’s citizens. Air pollution also contributes to climate change and damages ecosystems.

While emissions of many air pollutants such as sulphur dioxide and carbon monoxide have fallen over the past decades in the European region, air pollutant concentrations are still too high, according to the European Environment Agency.

Two of the major concerns are particulate matter and ozone: both affect human health and high levels of ozone also damages plants, harming farmers’ crops and also the growth of forests.

Where do air pollutants come from?

Nitrogen oxides

Nitrogen oxides are emitted during fuel burning, by things such as car engines, industrial facilities and household heating systems.

Sulphur dioxide

Sulphur dioxide is emitted when fuels containing sulphur are burned, or it comes from high temperature industrial processes involving raw materials high in sulphur content (such as smelters used for metal production).

Ozone

Ozone at ground level is formed by complex chemical reactions involving nitrogen oxides and also carbon monoxide and methane.

Carbon monoxide

Carbon monoxide is emitted due to incomplete burning of fossil fuels and biofuels.

Concern over air quality has led to new environmental protection policies and the creation of air-quality monitoring and forecast services in Europe. These services rely on data from satellites and ground-based monitoring stations.

GOME-2 and IASI – monitoring global air quality

The GOME-2 instruments aboard Europe’s Metop satellites play a key role in monitoring global air quality and its data is used to produce daily maps of ozone, nitrogen dioxide and sulphur dioxide.

The IASI instrument observes ozone and also carbon monoxide and methane.

Follow changes in air quality over Europe and the rest of the world.

Learn more about how satellites are used to monitor atmospheric composition (you'll need to create a free account with MetEd to view this)

Key Facts

The atmosphere regulates the Earth's temperature and filters out harmful rays from the Sun
It is divided into four areas; Troposphere, Stratosphere, Mesosphere and Thermosphere
Weather satellites keep an eye on the atmosphere, monitoring air quality and pollutants, ozone, trace and greenhouse gases, fires and aerosols
Concern over air quality has led to new environmental protection policies and the creation of air-quality monitoring and forecast services in Europe