THE EARTH’S ATMOSPHERE

The Atmosphere Is the layer of gasses that surrounds the Earth. The mixture of gasses that forms the atmosphere is called air. Air consists of nitrogen, oxygen and other gasses. The air also contains particles of dust and polluting gasses.

The atmosphere consists of nitrogen (78%), oxygen (21%), and carbon dioxide and other gasses (1%).

Atmosphere Structure:

Troposphere: Is the lowest layer and it reaches an altitude of about 15 km. It is where weather phenomena occur.

Stratosphere: This layer stretches from 15 km to 60 km above sea level. The ozone layer is located between 20 km and 40 km above the Earth's surface.

Thermosphere: This layer is between 60 km and 600 km above our planet. Artificial satellites orbit in it. It contains the ionosphere. The temperature in the thermosphere is very high. This is where aurora borealis are produced.

Exosphere: Extending from an altitude of 600 km, its upper part is very similar to interstellar space. It traps many of the particles the solar wind contains.

Composition of the Atmosphere: The atmosphere contains three gases that are essential for living things:

Oxygen: Produced by plants and used by all living things in respiration.

Carbon dioxide: Produced by all living things during respiration and used by plants in photosynthesis.

Nitrogen: Although it cannot be directly used by animals or plants, some bacteria transform it into compounds that plants can absorb.
The composition of the gases in the atmosphere is kept in balance thanks to photosynthesis and respiration.

PHOTOSYNTHESIS:

Plants produce their own food and oxygen (O₂) through the process of photosynthesis. This oxygen is released into the atmosphere.
To do this, they need carbon dioxide (CO₂), water and light energy.

RESPIRATION:

In respiration, oxygen is used to burn part of an organism's food in order to release energy.
Water and carbon dioxide are produced as a result, which are then incorporated back into the atmosphere.

CHARACTERISTICS OF AIR:

High transparency to light, which provides great visibility and higher efficiency in photosynthesis.
The propagation of sound, as sound waves are transmitted through the air.
Lift, a force which makes flight possible for flying organisms.

AIR POLLUTION:

Definition:
Air pollution can affect people and the environment in different ways. The main phenomena associated with air pollution are acid rain, the depletion of the ozone layer and global warming.

AIR POLLUTION:

Acid Rain → Factories, vehicle engines and heating boilers all emit nitrogen dioxide and sulphur dioxide. These gases combine with water vapour and oxygen in the atmosphere to form acids that fall along with precipitation.
Acid rain is harmful to the health of people and living things, soil and even buildings.

Depletion of ozone layer → The ozone layer filters ultraviolet radiation from the Sun.
The emission of gases composed of chlorine, fluorine and carbon from industries and aerosols depletes the ozone, making the layer thinner and causing damage to living things as a result of the increased exposure to ultraviolet radiation.

Global warming → Greenhouse gases retain some of the heat from the Sun that our planet reflects. This maintains the average temperature on the Earth at 15 °C, which is optimal for life. Without the greenhouse effect, the average temperature on the Earth would be -18 °C.

WIND AND ATMOSPHERIC PRESSURE:

Wind is the movement of air through the troposphere. The Sun heats the surface of the Earth, and the air that is in contact with the Earth's surface is heated and rises. Colder air coming from other places occupies the vacuum that is formed, creating wind.

  • The Sun heats the Earth's surface which, in turn, heats the air it is in contact with.

  • The hot air is less dense than the cold air and, therefore, it rises.

  • The rising hot air is replaced with new cooler air. This movement of the air is wind.

    ALTITUDES SICKNESS:

Altitude sickness is the name given to the organism's physiological reaction to exposure to the low oxygen pressure that exists at high altitude.
As we climb, there is a progressive decrease in the partial oxygen pressure, causing effects (headache, nausea, dizziness), which, if they continue for a long time, can cause death. This is why mountaineers often undergo a period of acclimatization during a climb to the summit, so that their body can adapt to these low oxygen pressures.