APES Weather and climate

Weather and Climate are closely related, yet distinct concepts that play a significant role in our daily lives and the environment.

• Weather: Describes the current physically conditions of the atmosphere (temp, moisture, pressure, wind)

• Climate: description of long-term pattern of weather in a particular area

• Both affect and are affected by human activities, and are the main determinants of the establishments of biomes and ecosystems.

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Atmospheric Development and composition 

• Earliest atmosphere believe to be composed of H gas and He, which is mostly diffused into space over billions of years

• Volcanic emissions added C, N, O, S and other trace elements into current composition 

• The evolutionary development of photosynthetic producers added O2.

•  Current atmospheric composition is primarily N2 gas, O2 gas, H2O vapor, aerosols, particulates.

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The ZONES of our layered atmosphere

• Troposphere

• Exist from the surface up to 18 km (tropopause), fairly uniform chemical composition, variable temperature dropping with increased altitude. 

• Stratosphere

• Extends from the tropopause (temperature gradient) up to 50 km, fairly stable temperature, 1000x lower moisture, 1000x greater ozone, earth's protective layer.

• Mesosphere

• Low temperature zone up to 80 km (ionosphere)

• Thermosphere

• High temperature zone, diminishing zone 

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Weather Generation

• The sun's insolation supplies the necessary heat and light energy

• The incoming solar radiation is either absorbed or reflected depending on the location albedo

• Greenhouse gasses such as carbon dioxide and methane efficiently trap the heat energy close to the surface creating the “Greenhouse Effect”, making earth life possible!

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The Role of Water in Weather Generation

• Convection currents: created by vertical density gradient of different temperature air masses carry with the large amounts of water vapor created by evaporation, this transfer of latent energy creates cyclical pressure gradients

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Weather Patterns (circulation of weather)

• The sun's energy is unevenly distributed due to the angle at which it strikes the earth's spherical shape, and the tilt of the planet. 

• convection currents are influenced by the earth's rotation, and the frictional drag close to the surface

• Coriolis Effect: spiraling wind patterns created by the convection currents that are influenced by the earth's rotation 

• *Prevailing winds are named for the direction in which they originate.   

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Jet Streams

• Undulating hurricane force winds at the top of the troposphere 

• Affects weather pattern

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Conflicting weather (storms)

• Front: The boundary between 2 air masses of different temperatures and density.

• Cold Front: occurs when a cooler moving air mass displaces warmer air

• Warm Front: occurs when a warmer moving air mass slides up and over a cooler air mass

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Storms

• Hurricanes: large cyclonic ocean storms with heavy rain and winds exceeding 74 mph

• Tornados: strong swirling winds and uplifts created when a strong cold front pushes under a warm moist air mass over land 

• Monsoons: A seasonal reversal of wing patterns caused by the different heating and cooling rates of ocean and continents creating prolonged heavy rains

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Natural Climate Variability

Milankovitch Cycles: are periodic shifts in the earth's orbits and axis tilt 

• Along with solar fluctuations, and galactic and geologic events, may explain major historical weather patterns.  (ex. Ice ages, el nino, la nina)

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Anthropogenic Climate Change

• Best evidence suggests recent human activity is increasing the “Greenhouse effect”, thus influencing global climate change. 

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What are the effects, why should you care?

• More extreme weather

• Droughts, floods, heat waves, hurricanes, sea level rise

• Loss/shift of habitat types

• Increased economic and human costs

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Solutions (KYOTO Protocol)

• Implementing emissions trading

• Technology sharing with less developed countries

• Modify behaviors (reduce deforestation, carbon capture, renewable energies)

• Helping poorer countries respond to climate change

Air Pollution

• Air Pollution: Foul, unclean, or dirty air

  • Can be naturally occurring (volcanoes, dust storms, sea spray, decomposition) or anthropogenic in origin, but concentration of airborne contamination in inhabited areas is almost entirely human caused

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Categories of Pollutants

•  Primary pollutants: Released directly from the source in a harmful form

• Secondary Pollutants: Modified to a hazardous form after release

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Conventional (criteria) pollutants: Contribute the largest volume of air-quality degradation, identified by E.P.A (clean air act 1970)

• Sulfur Oxide

  • SO2, SO3

  • Primarily generated by coal combustion and smelting

  • Acid Deposition: sulfuric acid precipitation, carried by prevailing winds, alter the pH of land and water

  • Economic

• Nitrogen Oxides

  • Nitric Oxide (NO)

  • Eye and lung irritant, cellular harm

  • (HNO3) nitric acid deposition 

• Carbon Oxides and Hydrocarbons

  • Carbon Dioxide (CO2) and Carbon Monoxide (CO), primarily from fossil fuel combustion, and cement production 

  • Methane (CH4) from decomposition and livestock farts and burps

  • CO gas is highly toxic 

  • Overload of greenhouse gases 

• Heavy Metals and Halogens 

  • Toxic metals such as Lead (Pb), Mercury (HG) and others, released during fossil fuel combustion, smelting, and waste incineration 

  • Chlorofluorocarbons (CFCs) from spray propellants and refrigerants 

  • Highly toxic materials, lead causes brain damage 

  • CFCs diffuse into the stratosphere and destroy the UV protective ozone layer leading to increases in skin cancer and blindness. 

Particulates and Aerosols

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• Respiratory distress

• Large-scale smog (often magnified due to inversion)

• Volatile Organic Compounds (VOCs)

  • Naturally occurring and synthetic organic compounds 

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Unconventional Pollutants

• Radon Gas

  • Carcinogen formed from the decay of naturally occuring uranium below ground 

• Aesthetic Degradation (excessive noice, odor, light)

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What can we do about air pollution

• Particulate Removal

  • Industrial filters, precipitators, and scrubbers

• Reduction (sulfur oxides, nitrogen oxides)

  • Limit use, cleaner burning fields, fossil fuel replacements. 

• Hydrocarbon Control

  • Minimize incomplete combustion