ATMOSPHERE
DEFINITION
COMPOSITION
STRUCTURE
The atmosphere is the layer of gases around the planet Earth. (Other planets canalso have an atmosphere). Atmósfera
The atmosphere is a mixture of gases.
According to their proportion, the most
important ones are: nitrogen (78%) and oxygen (21%).
The gases in the atmosphere are
forming a structure with layers.
Think of it as an onion, with
concentrical layers. These layers are:
Exosphere
Thermosphere
Mesosphere
Stratosphere
Troposphere
ATMOSPHERIC POLLUTION
Human activity produce gases and some solids that are very small and are able to be suspended in the atmosphere for long periods. Some of these substances are harmful for the people's health or other living organisms. They can also produce changes in natural processes, with terrible consequences.
Atmospheric pollution at the local scale: pollutants in the city
Atmospheric pollution at the global scale:
greenhouse effect, global warming
and climate change
In the cities there are lots of sources of pollutants: central heating, some factories... but the most important one is usually the traffic. Cars, trucks, buses and other vehicles produce lots of chemical substances. Some are very dangerous for human health
GREENHOUSE EFFECT
GLOBAL WARMING
CLIMATE CHANGE
We can find a small proportion of carbon dioxide in the atmosphere. It isn't harmful for humans but it has an effect on the Earth's temperature: 1.-Carbon dioxide (CO2) is a “greenhouse effect gas”. This means that this gas permits sunlights to go through the atmosphere. 2.-The sunlight in the ground increases its temperature. 3.-When the temperature of the ground increases it produce a different type of radiation: infrared radiation. 4.-Greenhouse effect gasses are not transparent to infrared radiation so they "catch" it. The heat is not able to go out the atmosphere so it rebounds heating the Earth again.
Due to the presence of these excess of greenhouse effect gases produced artificially by human action there are temperatures is increasing too much. As the process is happening all around the world we call it global warming. Mainly, it's produced by human activity and an increase of 0.1ºC could make huge changes in the Earth conditions.
As the temperature increases, all the rest of the climatic conditions change (rainfall,humidity,winds...). An increase of 2ºC in the temperatures produces changes in all the climatic conditions and also in other important issues such as an important rise of the sea level. We are not able to predict the exact changes in climate, but most of the models let us think of changes that are leading to more extreme climatic conditions (more draughts, more tornados, more floods... conditions which are going to be dangerous for most people).