PPT CHEM ATMOSPHERE

• Earth’s Atmosphere

  • Chemically active and  rich in oxygen.
  • Nurtures life and serves as a protection from the hostile environment of outer space.
  • The Earth’s Atmosphere is comprised of layers based on their different characteristics.
• Layers of The Atmosphere

  Troposphere

  • Earth’s troposphere extends from Earth’s surface to, on average, about 12 kilometers (7.5 miles) in height.
  • Temperatures typically go down the higher you go.
  • temperature drops  -56°C at the tropopause.
  • Holds all the air plants and animals need.
  • Contains 80 percent of mass of air and practically all of the atmosphere’s water vapor.
  • Densest atmospheric layer.
  • Most of Earth’s weather happens here, and almost all clouds that are generated by weather are found here.
• Stratosphere

  • Located between approximately 12 and 50 kilometers

   (7.5 and 31 miles) above Earth’s surface.

  • Temperature increases gradually -56º to 0ºC approaching the stratopause.
  • Consist of oxygen, nitrogen, and Earth’s ozone layer.
  • Nearly cloud- and weather-free.
  • It’s also the highest part of the atmosphere that jet planes can reach.
• Mesosphere

  • Located between about 50 and 80 kilometers (31 and 50 miles) above Earth’s surface.
  • The average temperature of -100ºC at the mesopause.
  • Gets progressively colder with altitude
  • Coldest layer of the atmosphere.
  • Most meteors burn up in this atmospheric layer.
• Thermosphere

  • Located between about 80 and 700 kilometers (50 and 440 miles) above Earth’s surface.
  • temperatures to increase in the Thermosphere and beyond. 
  • Contains the ionosphere.
  • The International Space Station orbits in here.
  • Auroras, the Northern Lights and Southern Lights occur here.
• Exosphere

  • Located between about 700 and 10,000 kilometers (440 and 6,200 miles) above Earth’s surface,
  • highest layer of Earth’s atmosphere and, at its top, merges with the solar wind.
  • Lowest part contains the ionosphere.
  • Most Earth satellites orbit in the exosphere.

  The lightest atmospheric gases such as hydrogen and helium exist throughout the exosphere.
• Atmospheric gases

  • Nitrogen (78%): Stable, non-reactive gas.
  • Oxygen (21%): Essential for life, used in respiration.
  • Argon (0.93%): Inert gas, stable.
  • Carbon Dioxide (0.04%): Small concentration, but critical for the greenhouse effect.
  • Trace Gases: Hydrogen, Krypton, Methane, Helium, Neon
• Molecular Nitrogen

  • Two nitrogen atoms tightly bound together.
  • About 78% of Earth's atmosphere is made up of molecular nitrogen (N2).
  • Very stable molecule with its triple bond.
  • Atmospheric nitrogen gas>nitrates and other compounds.
• Nitrogen Cycle

  • Biogeochemical process through which nitrogen is converted into many forms, consecutively passing from the atmosphere to the soil to organism and back into the atmosphere.
• Nitrogen Cycle

  • Nitrogen Fixation
  • Nitrification
  • Assimilation
  • Ammonification
  • Denitrification
• Nitrogen Fixation Process

  Atmospheric Nitrogen (N2) converted into the usable form - ammonia (NH3).
• Nitrogen Cycle

  Types of fixation

  • Atmospheric fixation
  • Industrial fixation
  • Biological fixation
• Nitrification Process

  • Ammonia is converted into nitrate by the presence of bacteria in the soil. 
  • Nitrites are formed by the oxidation of ammonia. 
  • Nitrites are converted into nitrates.
• Assimilation Process

  • Plants take in the nitrogen compounds (ammonia, nitrite ions, nitrate ions or ammonium) 
  • formation of the plant and animal proteins.
• Ammonification Process

  • Nitrogen present in the organic matter is released back into the soil. 

  The decomposers present in the soil, convert the organic matter back into ammonium
• Denitrification Process

  • Nitrogen compounds make their way back into the atmosphere.
  • denitrifying bacterial species which will process nitrate
  •  gain oxygen and gives out free nitrogen gas as a byproduct.
• Oxygen Cycle

  • The cycle of oxygen is the distribution of oxygen through nature in different ways. In order to respire, plants and animals use oxygen and return it as carbon dioxide (CO2) to the air and water.
• Oxygen Cycle

  • Stage-1: All green plants during the process of photosynthesis, release oxygen back into the atmosphere as a by-product.
  • Stage-2: All aerobic organisms use free oxygen for respiration.
  • Stage-3: Animals exhale Carbon dioxide back into the atmosphere. 
• Processes that occurs with the presence of Atmospheric Oxygen

  Breathing

  Decomposition

  Combustion

  Rusting
• Pollution

  • The Introduction of harmful materials into the environment. These harmful materials are called pollutants.
  • It has negative effects on the environment that may be harmful to humans and other living beings.
• Pollutants

  • Substance that is present in higher concentrations than would be expected due to human activity.
  • They are generally harmful to the environment and cause adverse effects on both humans and living beings.
• Contaminants

  • Substances that are recognized as foreign to the natural environment and might cause deviation from their normal composition.
  • If it causes detrimental effects, it is identified as a pollutant.
• Source

  • Where pollutants originate.
  • Ideally, this is the place to start to eliminate pollutants and pollution.
• Receptor

  • A medium that is affected by the pollutants.

  Ex. Eyes exposed to smoke released by motor vehicles.
• Sink

  • The medium, which reacts with the pollutants and acts as their long-term repository.

  Ex. Landfills
• Air Pollutants

  • The main cause of air pollution and global warming or the destruction of the protective stratospheric ozone layer.
  • These pollutants posed a serious problem that could threaten all the life living on earth. 
• Air Pollutants

  Carbon Dioxide “CO₂”

  • The most abundant type of air pollutant.
  • There are about 360 parts per million by volume in the atmosphere and are increasing 1 ppm per year.
  • This rapid increase in atmospheric CO₂ may cause intense global warming from the “greenhouse effect” that could pose a global threat.
• Greenhouse Effect

  • Gases in the atmosphere, such as carbon dioxide, trap heat similar to the glass roof of a greenhouse.
  • The greenhouse effect helps balance just the right temperature for humans and other living beings to thrive.
• Greenhouse Effect

  Human activities such as burning fossil fuels like coal and oil produce more than enough carbon dioxide that results in trapping more heat in the earth's atmosphere.
• Carbon Monoxide

  • Not a global threat like carbon dioxide.
  • This could cause serious health issues as it prevents blood from transporting oxygen to body tissues.
• Nitrogen Oxides

  • Nitric oxide (NO) and nitrogen dioxide (NO₂) which are collectively denoted as nitrogen oxides (NOx).
  • It primarily forms from the exhaust of motor vehicles.
  • It is extremely hazardous as it could form nitric acid (HNO₃), which is a very corrosive and harmful substance. 
  • Nitrogen dioxide can undergo photochemical reactions at a wavelength less than 430 nm.
  • This reaction produces highly reactive oxygen atoms, which sets off a chain reaction that produces chemicals in the atmosphere that are primarily harmful to the environment, people, and other living things.
• Sulfur Dioxide

  • Comes from the combustion of sulfur-containing fuels such as high-sulfur coal.
  • This sulfur dioxide reacts with the atmosphere, producing sulfuric acid (H₂SO₄).
  • These sulfuric acids are one of the main reasons for acid precipitation or acid rain.
  • The most abundant hydrocarbon in the atmosphere.
  • It is released from underground sources as natural gas and produced by the fermentation of organic matter.
  • One of the least reactive atmospheric hydrocarbons.
• Photochemical Smog

  • Photochemical smog is a mixture of air pollutants, creating a brown haze above cities.
  • These reactions happen when large amounts of pollutants are released in the atmosphere.
• Photochemical Smog

  • Smog means the combination of smoke and fog
  • Photochemical refers to the fact that it came from a chemical reaction involving light, which is identified as the sunlight.
  • Photochemical smog usually occurs in the summer season, where sunlight is most abundant for photochemical reactions to occur.
• Photochemical Smog

  Gases that set off a series of photochemical reactions are called primary pollutants, and the products of these reactions are called secondary pollutants, which are also mostly the substances responsible for producing the smog.
• What pollutants contribute to the formation of photochemical smog?

  Nitric oxides
• How do nitric oxides contribute to photochemical smog?

  They react with organic compounds in the atmosphere
• What role does sunlight play in the formation of photochemical smog?

  It causes the photochemical decomposition of NO₂
• At what wavelength does sunlight cause the decomposition of NO₂?

  Shorter than 400 nm
• What is produced from the photochemical decomposition of NO₂?

  NO and O