Atmosphere

• The atmosphere is the mixture of gases that surround the Earth.
• It is made up of 5 layers, troposphere, stratosphere, mesosphere, thermosphere and exosphere, the innermost two of which contain most of these gases.
• The troposphere, the layer nearest the Earth’s surface, contains most of the planet’s air: the mixture of gases that people depend on to stay alive.
• Troposphere is made up of 78% nitrogen, 21% oxygen, and 1% mixture of other gases like carbon dioxide, nitrous oxide, helium, and argon.
• The troposphere is responsible for maintaining the conducive temperature of the earth, allowing various organisms to thrive.
• The stratosphere is the Earth’s second layer of air.
• Stratosphere contains much of the atmosphere’s ozone gas (O3), which lies in a sub-layer of the lower stratosphere known as the ozone layer.
• This stratospheric ozone gas filter out about 95% of the sun’s harmful ultraviolet (UV) radiation before it can reach the Earth’s surface.
• There are four major problems involving the atmosphere namely, global warming, air pollution, acid deposition, and ozone depletion.
• Global warming refers to the accelerating rate in the increase of the average global temperature.
• Global warming is due to the rapid increase in greenhouse gases found in the atmosphere due to anthropogenic activities.
• Greenhouse Effect: Solar radiation that reaches the surface of the earth is absorbed and then re-emitted back by the heated surface as infrared radiation (IR).
• Infrared radiation is the heat that we feel if we touch a surface that has absorbed solar radiation.
• If there is no atmosphere, the infrared radiation freely escapes into space. However, the heat absorbing components of the atmosphere prevent the IR from escaping, thus the heat is trapped on earth, this is greenhouse effect.
• Among the components of the atmosphere, nitrogen and oxygen absorb little or no radiation. However, the minor components are the effective absorbers of IR particularly carbon dioxide and water vapor. These gases are responsible for the greenhouse effect thus called greenhouse gases.
• Once infrared radiation is absorbed by greenhouse gases, it is once again re-emitted in all directions, warming the surrounding air.
• Warming the earth is an especially important natural process.
• The more the greenhouse gas, the more heat is trapped by the atmosphere, the warmer the earth. This is called global warming.
• Greenhouse effect:

  1. Sun's radiation travels toward Earth.
  2. Some of the energy is reflected and the rest of it is absorbed by the Earth's atmosphere.
  3. The Earth re-emits heat back to the space.
  4. Some of this energy passes directly through the atmosphere.
  5. But greenhouse gases trap most of it, keeping the planet warm.
• Causes of Global Warming

  1. Burning of Fossil Fuel

  Fossil fuels such as coal, crude oil, and natural gas, are formed for millions of years from buried remains of plants and animals, thus rich in carbon content.

  When these are burned, the carbon content is released into the atmosphere in the form of carbon dioxide, a major greenhouse gas
• Causes of Global Warming

  1. Burning of Fossil Fuel

  • there are also the increased amounts of tiny particles in the lower atmosphere that scientists call ‘black carbon’ (soot or smoke).
  • while it is suspended in the air, it absorbs the sun’s heat millions of times more effectively than CO2.
  • Overall, it is considered the second biggest contributor to global warming after CO2.
• Causes of Global Warming

  1. Burning of Fossil Fuel

  • Methane, another greenhouse gas, is also released in the atmosphere by this process
• Causes of Global Warming

  2. Deforestation

  • Photosynthetic organisms absorb carbon dioxide from the atmosphere
  • Trees are the largest photosynthetic organisms and responsible for absorbing the greatest amounts of carbon dioxide from the atmosphere
  • Most trees on earth are found in forests, making these ecosystems especially important in regulating the amount of carbon dioxide in the atmosphere
• Causes of Global Warming

  2. Deforestation

  • Human activities that lead to the removal or destruction of vast amounts of trees is called deforestation
  • Reducing the trees available for carbon dioxide absorption relates to an increase in this greenhouse gas and therefore an increase in global warming
• Causes of Global Warming:

  3. Agriculture and Farming Practices

  • Methane is a greenhouse gas that is produced by the anaerobic decomposition of organic matter, such as animal wastes and dead plant materials, which is a natural process
  • However, increased agricultural activities have also greatly increased the amount of organic matter available for anaerobic decomposition, being the number one cause of methane release in the atmosphere
• Effects of Global Warming:

  Climate Change is a long-term change in the average weather patterns that have come to define Earth’s local, regional, and global climates.

  With global warming, the climatic patterns of the earth changed rapidly, especially for cold areas.
• Effects of global warming, Indicative of climate change:

  • Melting and shrinking of ice sheets in the Arctic Sea, decrease snow cover of ice-capped mountains, and glacial retreat, all of which bring about a rise in sea level and coastal submersion.
• Effects of global warming, Indicative of climate change:

  • Intensified weather disturbances that bring about intense rain and wind (la Niña phenomenon), as well as prolonged droughts and heat wave (el Niño phenomenon)
• Effects of global warming, Indicative of Climate Change:

  • Biomes are defined by their climatic characteristics, to which organisms are adapted to. Change in climatic conditions of biomes likewise affect organismal survival and decreases biodiversity and loss of ecological balance
• Effects of global warming, Indicative of climate change:

  • Food crops are likewise vulnerable to climatic changes, leading to a decline in the food supply of the global population.
• Effects of global warming, Indicative of climate change

  • High rates of evaporation dry up lands, reduce freshwater supply, and lead to desertification
• Dealing with Global Warming

  1. Decrease Fossil Fuel Use

  • Conservation of energy
  • Use of renewable energy resources such as solar energy, wind energy, hydrogen energy, ocean energy, hydro power, geothermal power, and bioenergy
• Dealing with Global Warming

  2. Reforestation and Afforestation

  • Reforestation is the process of planting trees in a forest where the number of trees has been decreasing.
  • Afforestation is when new trees are planted or seeds are sown in an area where there were no trees before, creating a new forest.
• Dealing with Global Warming:

  3. Enacting global and national laws and agreements

  • Steep penalties for non-compliant industries and businesses
  • Regulating and taxing carbon dioxide emissions of companies
• 4. Sustainable land management

  • Managing livestock to reduce methane emission
  • Crop management to avoid methane and nitrous oxides, such as from fertilizers
• Air pollution is the presence of chemicals in the air, called air pollutants, at levels high enough to harm humans, other organisms, ecosystems, or human-made materials.
• Primary air pollutants include all chemicals that are emitted directly into the air from natural processes and human activities and that are build up to harmful levels.
• Secondary air pollutants are harmful chemicals that form in the air by reacting with primary pollutants or with chemicals naturally found in the air.
• Major Air Pollutants

  1. Sulfur dioxide
  2. Nitrogen oxide
  3. Carbon monoxide
  4. Ozone and Photochemical oxidants
  5. Lead
  6. Particulate matter
  7. Mercury from coal
• Causes and Sources of Air Pollution

  1. Indoor/household air pollution

  • Solid fuels such as charcoal, peat, coal, wood pellets, corn, wheat, rye and other grains that can be burnt to release energy
  • Kerosene for cooking or oil lamps release the pollutants ethylene, Sulphur dioxide, and nitrogen oxide
  • Products with volatile organic compound (VOCs) such as air fresheners and cleaning products