Earth's Atmosphere and Climate Change Concepts

Unit 7: Atmosphere

4.4 Earth’s Atmosphere

  • Composition of the Atmosphere

    • 99% is made of two elements:
    • 78% Nitrogen
    • 21% Oxygen
    • 1% consists of CO2, Argon, water vapor, & others.
    • Water Vapor varies based on air origin:
    • Dry air from land, moist air from water.
    • Origin of gases from volcanic eruptions.

  • Structure of the Atmosphere

    • Layers of the Atmosphere: Determined by temperature changes.

    • 99% of the atmosphere lies within 30 km of the Earth’s surface.

    • Main Layers:

    • Troposphere:

      • Lowest layer, all weather occurs here, temperature decreases with altitude.

    • Stratosphere:

      • Ozone layer located here, absorbs UV radiation, temperature increases with altitude.

    • Mesosphere: Coldest layer.

    • Thermosphere: Hottest layer, divided into ionosphere (northern lights, meteors break up) and exosphere (outer space).

4.5 Global Wind Patterns

  • Air Movement:

    • Air moves from high pressure (warm/sunny) to low pressure (cold).
    • Winds Named for Direction: Where they come from.

  • Coriolis Effect:

    • Air deflects due to Earth's rotation; right in the Northern Hemisphere, left in the Southern Hemisphere.
    • Causes circular ocean gyres and cyclonic storms.

  • Convection Currents:

    • Air rises at 0° & 60° N/S, sinks at 30° & 90° N/S.
    • Includes Hadley Cells (0° to 30°) and Ferrel Cells (30° to 60°).

  • Trade Winds:

    • Named for origin: North East (0° to 30° N) & South East (0° to 30° S).
    • Westerlies (30° to 60° N/S) and Polar Easterlies (60° to 90° N/S).

4.7 Solar Radiation & Earth's Seasons

  • Solar Radiation (Insolation):

    • Source of 99% of Earth’s energy.
    • 31% reflected by clouds, land, and oceans (Albedo).

  • Natural Greenhouse Effect:

    • Energy from the sun is trapped by greenhouse gases (GHGs) in the atmosphere, keeping Earth warm.
    • Definition: Trapping sun’s warmth in the lower atmosphere.

  • Climate & Seasons:

    • Seasons result from the tilt of the Earth (23.5°), not distance from the sun.
    • Key latitude lines:
    • Tropic of Cancer (23° N): Highest latitude of direct overhead sun (Summer Solstice).
    • Tropic of Capricorn (23° S): Lowest latitude of direct overhead sun (Winter Solstice).

  • Solstices & Equinoxes:

    • Summer Solstice (June 21): Longest daylight in Northern Hemisphere.
    • Winter Solstice (December 21): Shortest daylight.
    • Equinoxes: Equal day and night.
    • Autumnal: September 22, Vernal: March 20.

4.9 El Niño & La Niña

  • El Niño Southern Oscillation (ENSO):
    • SE trade winds weaken, reducing warm water push towards Australia; results in upwelling reduction.
    • Occurs every 3-5 years; causes wetter conditions in western South America and droughts in Australia.
    • La Niña: stronger trade winds, cooler ocean.

7.1 Introduction to Air Pollution

  • Types of Air Pollutants:

    • Two Forms: Parts per million (ppm) & parts per billion (ppb).
    • Particulate Matter: Solid and liquid particles, sources include dust, smoke, and ash, can be natural or anthropogenic.

  • Primary vs. Secondary Pollutants:

    • Primary: Emit directly into the atmosphere (e.g., CO2, SO2).
    • Secondary: Formed from reactions of precursors (e.g., ozone from NOx + VOCs).

7.2 Photochemical Smog

  • Definition: Smog is a mixture of fog and smoke with pollutants.
  • Photochemical Smog:
    • Produced from NOx and VOCs in sunlight, leads to ground-level ozone.
    • Common in urban areas during summer.

9.1 Stratospheric Ozone

  • Ozone Layer:
    • Protects from harmful UV radiation, located in the stratosphere.
    • Ozone Depletion:
    • Caused by anthropogenic factors like CFCs, leading to increased UV exposure on Earth.
    • CFCs are also GHGs, contributing to warming.

9.3 The Greenhouse Effect

  • Greenhouse Gases (GHGs):
    • Measured by Global Warming Potential (GWP).
    • CO2 has a GWP of 1; methane (CH4) has a GWP of 21, while CFCs have thousands.

Important Notes

  • Global Warming vs. Climate Change:
    • Global warming is a result of human activities increasing GHGs, while climate change includes all changes in climate dynamics.
  • Health Impacts of Ozone & Other Pollutants:
    • Ozone (tropospheric) can lead to respiratory issues, while stratospheric ozone is protective.

Laws & Protocols

  • Clean Air Act:
    • Regulates air emissions, sets standards for pollutants, requires states to monitor and reduce air quality issues.
  • International Agreements:
    • Kyoto Protocol: Aimed to reduce GHG emissions by 5.2% below 1990 levels.
    • Paris Agreement: Seeks to limit global warming to below 2°C.