THE ATMOSPHERE

The composition of air Air consists mainly of nitrogen, oxygen, carbon dioxide, water vapour, and many other gases in small amounts, such as ozone.  Nitrogen (N 2 ) makes up 78% of the gases in the air. Not many living things are capable of using it, however, it is a component that is present in all living things.  Oxygen (O 2 ) makes up 21% of the total. It is essential gas for respiration. It is produced by plants in the process of photosynthesis.  Carbon dioxide (CO 2 ) is 0.033% of the total. Plant use it for photosynthesis. Living things release it through respiration.  As well as these gases there are others such as ozone, hydrogen, argon, krypton, helium and neon.  Air can also contain water vapour (H 2 O) in variable quantities. Water vapour helps warm the surface of the Earth, is essential for the water cycle and for climate.

The atmosphere is not uniform. Its gases concentrate in the zone nearest the Earth due to the weight of the air. The temperature of the atmosphere varies with altitude and allows us to identify five layers within it.

The troposphere  The troposphere stretches from the surface of the Earth to an altitude of 12 km.  It contains most of the atmosphere’s air (around 80%).  Living beings develop in it.  In this layer is where meteorological phenomena take place, so clouds are formed.  It´s where human beings live.

The stratosphere  The stratosphere is located between 12 km and 50 km above the Earth’s surface.  This is where we find the ozone (O 3 ) layer. This gas is very beneficial to living beings because it filters most of the Sun’s ultraviolet rays, which are harmful to life.  Beyond this layer, only about 1% of the atmosphere´s mass remains.

The mesosphere  The mesosphere is located between 50 km and 85 km above the Earth’s surface.  Most small meteorites which reach the Earth disintegrate in this layer, producing what we call ‘shooting stars’.

The thermosphere or ionosphere  The thermosphere is located between 85 km and 600 km above the Earth’s surface.  In this layer, the Sun’s most harmful radiation is filtered.  Most satellites orbit in this layer.  It is characterized by high temperatures.  In this layer auroras are generated.

The exosphere  The exosphere extends beyond 600 km above the Earth’s surface.  The amount of air in this layer is very small and gets progressively smaller until reaching outer space. It has no clear boundary.  There are also satellites.

THE ATMOSPHERE GASES QUIZ

TRUE OR FALSE. EXPLAIN YOUR ANSWER: Others gases in the atmosphere are: ozone, hydrogen, sulfuric acid, krypton, glucose and neon.

It makes up 21% of the total.

Plant use it for photosynthesis.

It makes up 78% of the gases in the air

It helps warm the surface of the Earth, is essential for the water cycle and for climate.

It is produced by plants in the process of photosynthesis.

It is 0.033% of the total

It is essential gas for respiration.

Living things release it through respiration.

Not many living things are capable of using it, however it is a component that is present in all living things. For example in the DNA.