The Earth's atmosphere is made of layers of gases which are retained by the Earth's gravity. Some planets, such as Jupiter are among the ‚ÄúGas Giants‚Äù which consist mainly of gases and thus, have very deep atmospheres. Earth contains roughly (by molar content/volume) 78% nitrogen, 20.95% oxygen, 0.93% argon, 0.038% carbon dioxide, trace amounts of other gases and a variable amount (average around 1%) of water vapour, together, it is commonly known as air. The density of air at sea level is about 1.2 kg/m3. This well-balanced composition protects life on Earth by absorbing ultraviolet solar radiation and reducing temperature extremes between day and night.
Atmospheric pressure is the force (per unit area) that is applied perpendicularly to a surface by the surrounding gas. It is determined by a planet's gravitational force and the total mass of a column of air above a location. Surface gravity, the force that holds down an atmosphere, differs significantly among the planets. The distance from the sun determines the energy available to heat atmospheric gas to the point where its molecules' thermal motion exceeds the planet's escape velocity, the speed at which gas molecules overcome a planet's gravitational grasp. Since a gas at any particular temperature will have molecules moving at a wide range of velocities, there will almost always be some slow leakage of gas into space. Earth's magnetic field helps to minimise this.
The Earth is made up of six different atmospheric layers:
1.¬†¬†¬†¬†¬†¬† Troposphere; the lowest layer which begins from the surface and extends to between 7 km at the poles and 17 km at the equator. It contains roughly 80% of the total mass of the atmosphere and maintains life on earth.
2.¬†¬†¬†¬†¬†¬† Stratosphere; extends from the troposphere's 7 to 17 km range to about 50 km and contains the ozone layer, which protects life from ultraviolet radiation.
3.¬†¬†¬†¬†¬†¬† Mesosphere; extends from about 50 km to the range of 80 to 85 km, which is also where most meteors burn up when entering the atmosphere and help protect earth from the constant bombardment of galactic debris.
4.¬†¬†¬†¬†¬†¬† Thermosphere is from 80 ‚Äì 85 km to 640+ km where the temperatures changes widely with height. ¬†
5.¬†¬†¬†¬†¬†¬† Ionosphere; is the part of the atmosphere that is ionised by solar radiation. It plays an important part in atmospheric electricity and is responsible for auroras.
6.¬†¬†¬†¬†¬†¬† Exosphere; from 500 ‚Äì 1000 km up to 10,000 km which are made up of free-moving particles.
From the perspective of the planetary geologist, the atmosphere is an evolutionary agent essential to the morphology of a planet. The balance of Oxygen and Carbon Dioxide in the atmosphere is vital to sustain life on earth. Both are maintained by biological productivity and geological forces working hand-in-hand to maintain reasonably steady levels. Air pollution is a chemical, physical (e.g. particulate matter) or biological agent that modifies the natural characteristics of the atmosphere in an unwanted way.
Stratospheric ozone depletion caused by air pollution is a threat to human health and the earth's ecosystems. Worldwide air pollution is responsible for large numbers of deaths as well as respiratory diseases. The greatest sources of emissions are mobile sources, principally the automobile. Gases such as carbon dioxide, methane, and fluorocarbons contribute to global warming. There are many substances in the air which may impair the health of plants and animals (including humans), or reduce visibility. These arise both from natural processes and human activity. Substances not naturally found in the air or at greater concentrations or in different locations from usual are referred to as 'pollutants'.
Some of the primary pollutants produced by human activity include:
- Gases: Sulphur oxides (SOx) from burning of coal and oil, Nitrogen oxides (NOx) from high temperature combustion, Carbon monoxide a very poisonous gas, produced by incomplete combustion of fuel such as natural gas, coal or wood, Carbon dioxide (CO2), a greenhouse gas emitted from combustion and respiration.
- Volatile organic compounds (VOC) from such as hydrocarbon fuel vapours and solvents and is a major source of indoor pollution which badly effects the indoor health of a dwelling.
- Particulate matter (PM) from fossil/forest burning can enter the bronchus and lungs, reducing its efficiency.
- Toxic metals, such as lead, cadmium and copper from industrial processes, which can cause heavy metal poisoning.
- Chlorofluorocarbons (CFCs), harmful to the ozone layer emitted from products currently banned from use.
- Ammonia (NH3) emitted from agricultural processes.
- Odours, such as from garbage, sewage and industrial processes
- Radioactive pollutants produced by nuclear explosions and war explosives.
Acid rain is the deposition of acidic components in rain, snow, fog, dew, or dry particles. Unpolluted rain has a slightly acidic pH of 5.6, because carbon dioxide and water in the air react together to form carbonic acid, a weak acid. The extra acidity in rain comes from the reaction of air pollutants; primarily sulphur oxides and nitrogen oxides, with water in the air to form strong acids (like sulphuric and nitric acid). Occasional pH readings of well below 2.4 (the acidity of vinegar) have been reported in industrialized areas such in China, Eastern Europe and Russia.
Earth‚Äôs atmosphere is a well-balanced, flawless and wondrous creation. Allah says:
‚ÄúDo they not look at the sky above them - how We have built it and made it beautiful and free of all faults?‚Äù [Quran 50:6]
He also says:
‚ÄúIt is God who has made the earth a resting- place for you and the sky a canopy, and has formed you - and formed you so well‚Äù [40:64]
The atmosphere is a canopy which is well secured in its foundation [21:32]. A canopy or roof (building) is an architectural projection that provides weather protection, identity or decoration, and is supported by the building to which it is attached which acts as a protector against the elements such as the cold, wind, rain, etc. but still admits other wanted elements like light inside.
We are told that He brings life from the sky,
‚ÄúVerily, in the creation of the heavens and of the earth, and the succession of night and day: and in the ships that speed through the sea with what is useful to man: and in the waters which God sends down from the sky, giving life thereby to the earth after it had, been lifeless, and causing all manner of living creatures to multiply thereon: and in the change of the winds, and the clouds that run their appointed courses between sky and earth: [in all this] there are messages indeed for people who use their reason‚Äù [2:164]
However, we turn this life giving, protecting creation into that which brings disease and death. Allah sent water from the sky in a sweet and palatable form but we turn them into ‚Äòvinegar‚Äô. ¬†
As God has willed for Him to be the unseen power from which all originates, He created Earth and enveloped it with an unseen canopy of protection for life to thrive. And like its creator, although this canopy is unseen; its presence - felt, its protection - received, and its sustenance - enjoyed. This canopy lets live giving light enter and keeps all that is destructive out. This canopy runs its course, between the earth and sky and helps sustain life, secured firmly by Earth‚Äôs gravity. And just like we treat the unseen God, we do not give thanks for this unseen envelop of power, but when a dweller pokes a hole in his home‚Äôs roof, who is he really hurting? Who is the loser? Who will taste the fruits of his act? If our eyes are limited in its sight, is our mind also limited in its understanding and wisdom?
‚ÄúAre they, then, not aware of how little of the sky and the earth lies open before them, and how much is hidden from them?‚Äù [34:9]