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