Chemistry of the Atmosphere and Climate Change

Atmosphere Composition

99% nitrogen and oxygen near Earth's surface.

Non-Uniform Gas Distribution

Gas composition varies with altitude and location.

Troposphere

Lowest atmospheric layer; where weather occurs.

Stratosphere

Second layer; contains ozone layer absorbing UV-B.

Mesosphere

Middle layer; meteors burn up here.

Thermosphere

Upper atmosphere; very few molecules present.

Solar Wind

Charged particles emitted from the Sun.

Auroras

Light displays formed in the thermosphere.

Particle Collisions

Electrons excite atmospheric molecules, emitting light.

Red Auroras

Above 200 km; caused by oxygen molecules.

Blue Auroras

100-200 km; caused by nitrogen molecules.

Green Auroras

100-200 km; caused by oxygen molecules.

Pink Auroras

Below 100 km; caused by nitrogen molecules.

Photodissociation

Chemical bond rupture from photon absorption.

Photoionization

Molecule absorbs radiation, ejects electron, becomes ion.

Ionization Energy

Energy needed to remove an electron from an atom.

Wavelength (λ_max)

Maximum wavelength for ionization of specific molecules.

O2 Dissociation Energy

498 kJ/mol required to break O2 bond.

Planck's Equation

E=hν relates energy to photon frequency.

Speed of Light Equation

c=λν relates speed, wavelength, and frequency.

Avogadro's Number

6.022 x 10^23; used for mole calculations.

Ultraviolet Radiation

Short wavelength radiation; can cause ionization.

Ozone Layer

Protective layer absorbing harmful UV radiation.

Meteors

Burn up in the mesosphere due to friction.

Excited Atoms

Atoms with electrons in higher energy states.

Aurora Formation Process

Involves solar wind, collisions, and light emission.

Reactive Oxygen

Oxygen's lower bond enthalpy makes it more reactive.

Ion Presence

Enables long-range radio communication in the atmosphere.

Ozone Layer

Protective gas ring absorbing harmful UV rays.

Stratosphere

Layer of atmosphere where ozone layer is located.

Ozone Thickness

2 to 8 mm under normal conditions.

UVA Rays

Most common UV rays causing skin aging.

UVB Rays

Causes sunburns, cataracts; 95% absorbed by ozone.

UVC Rays

Most dangerous UV rays; 100% absorbed by ozone.

Photokeratitis

Eye injury caused by UV radiation exposure.

Ozone Absorption Range

Ozone absorbs radiation between 240 and 310 nm.

Ozone Formation

Occurs through O₂ and free oxygen atom reaction.

Photodissociation

Process where UV radiation splits oxygen molecules.

Chemical Reaction for Ozone

O + O₂ → O₃ forms ozone.

Ozone Depletion Discovery

1974 discovery of CFCs harming ozone by Rowland and Molina.

CFCs

Chlorofluorocarbons used in aerosols and refrigerants.

HCFCs

Hydrochlorofluorocarbons; less harmful than CFCs.

Halon

Used in fire extinguishers; ozone-depleting chemical.

Methyl Bromide

Pesticide contributing to ozone depletion.

Ozone Depletion Process

CFCs release chlorine, which reacts with ozone.

Chlorine Monoxide

Product of ozone breakdown by chlorine.

Ozone Hole

Area of severe ozone depletion, notably over Antarctica.

Dobson Unit (DU)

Standard measurement for ozone concentration; 1 DU = 0.01 mm.

Ozone Hole Monitoring

NASA tracks ozone hole size and extent.

UV Radiation Effects

Increased exposure leads to skin cancer and eye damage.

Ozone Layer Importance

Shields life from harmful UV radiation.

Ozone Depletion Impact

Affects ecosystems, increases health risks.

Ozone Layer Shielding

Critical for protecting life from UV radiation.

UV Radiation Types

Includes UVA, UVB, and UVC with varying effects.

Ozone Layer Environmental Concern

Depletion allows more harmful UV radiation to reach Earth.

Ozone Formation Process Steps

UV radiation splits O₂, forming ozone through collisions.

CFCs

Chlorofluorocarbons that deplete ozone layer.

UV radiation

Ultraviolet light causing CFC bond breakage.

Chlorine atoms

Released from CFCs, react with ozone.

Ozone (O₃)

Ozone layer protects Earth from UV radiation.

Chlorine monoxide (ClO)

Intermediate product in ozone depletion cycle.

Montreal Protocol

1987 agreement to phase out CFCs.

Troposphere

Lowest atmospheric layer, contains weather.

Carbon dioxide (CO₂)

Greenhouse gas from organic matter decomposition.

Carbon monoxide (CO)

Toxic gas from incomplete combustion.

Methane (CH₄)

Greenhouse gas from organic matter decomposition.

Nitric oxide (NO)

Pollutant from combustion engines and discharges.

Ozone (O₃) in troposphere

Harmful pollutant, differs from stratospheric ozone.

Sulfur dioxide (SO₂)

Gas from burning fossil fuels, contributes to acid rain.

Acid rain

Precipitation containing sulfuric or nitric acids.

Sulfur trioxide (SO₃)

Forms from oxidation of sulfur dioxide.

Sulfuric acid (H₂SO₄)

Result of SO₃ reacting with water.

Calcium carbonate (CaCO₃)

Limestone used in reducing SO₂ emissions.

Calcium oxide (CaO)

Product of heating limestone, reacts with SO₂.

Calcium sulfite (CaSO₃)

Formed from CaO and SO₂ reaction.

Scrubber system

Aqueous suspension removing CaSO₃ from emissions.

Nitrogen oxides (NOₓ)

Pollutants contributing to photochemical smog.

Photochemical smog

Smog formed from sunlight-driven reactions.

Nitrogen dioxide (NO₂)

Main component of urban smog haze.

Smog

Mix of smoke and fog, worsened by weather.

Greenhouse effect

Trapping of heat by greenhouse gases.

Respiratory issues

Health problems linked to air pollution.

Pollutants

Substances causing environmental harm.

Decomposition

Breakdown of organic matter releasing gases.

NO₂

Nitrogen dioxide, key in ozone formation.

O₃

Ozone, a pollutant formed from NO₂.

Respiratory Issues

Health problems like asthma and lung damage.

Visibility Reduction

Decreased sight due to air pollution.

Ecosystem Damage

Harm to plants and natural habitats.

Catalytic Converters

Devices reducing NOₓ emissions in vehicles.

Public Transport

Shared transport options to lower fossil fuel use.

Electric Vehicles

Cars powered by electricity, reducing emissions.

Industrial Smog

Grayish pollution from burning coal or oil.

Photochemical Smog

Brownish pollution from vehicle emissions and sunlight.

London Smog

Historical industrial smog associated with London.

L.A. Smog

Smog formed in Los Angeles from vehicles.

Sulfur Oxides (SO₂)

Main pollutants in industrial smog.

Nitrogen Oxides (NOₓ)

Key pollutants in photochemical smog.

Greenhouse Effect

Atmospheric phenomenon retaining Earth's heat.

Carbon Dioxide (CO₂)

Major greenhouse gas from fossil fuel combustion.