Earth's Atmosphere and Global Warming

• The atmosphere is a mixture of gases surrounding the Earth
• It has 5 layers, each with different functions

Troposphere

• Closest to Earth
• Contains 78% nitrogen, 21% oxygen, and 1% other gases, including carbon dioxide, helium, and argon
• Contains water vapor that helps regulate Earth's temperature
• Site of weather occurrences

Stratosphere

• Above the troposphere
• Contains the ozone layer, which protects from the sun's harmful UV rays
• Commercial jets fly here because it has stable weather

Mesosphere

• The coldest layer of the atmosphere
• Burns up most meteors before they reach Earth

Thermosphere

• The hottest layer of the atmosphere
• Where auroras (Northern and Southern Lights) occur
• The International Space Station orbits in this layer

Exosphere

• Outermost layer
• The boundary between Earth's atmosphere and space
• Contains very few air molecules

Global Warming

• Definition: An increase in Earth's average temperature due to excess greenhouse gases
• Cause: Human activities release too much carbon dioxide (CO2), methane (CH4), and other greenhouse gases
• Sunlight reaches Earth, and the surface absorbs heat
• Greenhouse gases trap this heat, keeping the Earth warm
• Too much greenhouse gas = too much heat trapped = global warming
• Main Causes of Global Warming:
  • Burning fossil fuels (coal, oil, gas) releases carbon dioxide
  • Deforestation reduces trees that absorb CO2
  • Agriculture releases methane from animal waste and fertilizers
• Effects of Global Warming:
  • Climate Change (changing weather patterns, stronger storms, heatwaves)
  • Melting glaciers - Rising sea levels - Coastal flooding
  • Destruction of ecosystems - Loss of biodiversity
  • Food and water shortages
• How to Reduce Global Warming:
  • Use renewable energy (solar, wind, hydro)
  • Plant more trees
  • Regulate industries that release CO2
  • Use energy efficiently

Air Pollution

• Definition: Presence of harmful chemicals in the air
• Two types:
  • Primary pollutants: Released directly (e.g., smoke from factories, cars, burning fuel)
  • Secondary pollutants: Formed by chemical reactions in the air (e.g., smog)
• Major Air Pollutants:
  • Sulfur dioxide (SO2) - From burning coal, causes acid rain
  • Nitrogen oxides (NOx) - From vehicles and factories, cause smog
  • Carbon monoxide (CO) - From burning fuel, toxic to humans
  • Ozone (03) - Harmful when at ground level
  • Lead - From industries, harms health
• Effects of Air Pollution:
  • Respiratory diseases (asthma, lung infections)
  • Acid rain (damages buildings, soil, and water)
  • Harm to crops and forests
• Ways to Reduce Air Pollution:
  • Use clean energy (solar, wind, hydropower)
  • Limit factory and vehicle emissions
  • Laws like the Clean Air Act to control pollution

Acid Deposition (Acid Rain)

• Definition: When pollutants mix with water in the air and fall as acidic rain
• Cause: Burning coal and gas releases sulfur dioxide (SO2) and nitrogen oxides (NOx), which turn into acid in the atmosphere
• Effects of Acid Rain:
  • Harms forests and soil (removes nutrients, weakens plants)
  • Lowers pH of water bodies, killing fish and other organisms
  • Damages buildings and statues
  • Health problems (lung diseases, toxic metals in water)
• Ways to Reduce Acid Rain:
  • Reduce fossil fuel use
  • Switch to renewable energy
  • Neutralize acid in lakes (using lime)

Ozone Layer Depletion

• Definition: The thinning of the ozone layer, which protects Earth from harmful UV rays
• Cause: Human-made chlorofluorocarbons (CFCs) found in old refrigerators, air conditioners, and spray cans
• More UV rays reach Earth, causing:
  • Skin cancer
  • Eye damage (cataracts)
  • Weakened immune system
  • Harm to plants and marine life
• How to Protect the Ozone Layer:
  • Ban CFCs (Montreal Protocol 1987)
  • Use ozone-friendly products
  • Support research on safer chemicals