Atmospheric Science and Air Pollution

Atmospheric Science and Air Pollution Chapter 17

Central Case: Charging toward Cleaner Air in London • No city can claim a longer or more notorious history of air pollution than London, England. • “killer smog” – 4-12,000 killed (1952) • Smog - (Unhealthy mixture of air pollutants over urban areas) - cocktail of pollutants of carbon dioxide, carbon monoxide, nitrogen oxides, and particulate matter (Solids/liquids suspended in the atmosphere). • REDUCED CONGESTION AND IMPROVED VEHICLE TECHNOLOGY • Charge drivers a fee for entering the central city ($15.00) • Traffic congestion decreased by nearly 30% • Particulate matter decline by 15.5% • Nitrogen oxide emissions decreased by 13.4% • Carbon dioxide emissions fell by 16.4%

Tropopause- cap limiting mixing between the troposphere and stratosphere. TR-earth ST-ozone ME- little ozone TH- O2 The Atmosphere

Layers of the Atmosphere • Troposphere • Bottommost layer • Provides us the air • Responsible for the planet’s weather • ¾ of the atmosphere’s mass because air is denser near Earth’s surface • Stratosphere • Drier and less dense than the troposphere • Little vertical mixing (pollutants remain a long time) • Ozone layer – reduce UV light penetration • Mesosphere • Low air pressure/temperature decrease with altitude • Thermosphere • Top layer • Exosphere • The region where atoms and molecules escape into space

Atmospheric Properties • Lower atmosphere is stable in its chemical composition, but dynamic (strong/powerful) in its movement; air movement within it is due to differences in the physical properties of air masses. These properties are pressure and density, relative humidity, and temperature. • 1.Atmospheric pressure • Measures the force per unit area produced by a column of air. • Decrease with altitude – fewer molecules are pulled by gravity • Sea level – 1 atm, 14.7 lb/in2, 760 mm Hg, 101.3 kPa, 1013 mb

2.Relative Humidity • Ratio of water vapor a given volume of air contains to the maximum amount it could contain at a given temperature (Increase temperature decrease relative humidity) • YouTube Search Powered by iBoss • Relative humidity is the ratio of the current absolute humidity to the highest possible absolute humidity (which depends on the current air temperature). A reading of 100 percent relative humidity means that the air is totally saturated with water vapor and cannot hold any more • Humans are very sensitive to humidity, as the skin relies on the air to get rid of moisture. The process of sweating is your body's attempt to keep cool and maintain its current temperature. If the air is at 100-percent relative humidity, sweat will not evaporate into the air. As a result, we feel much hotter than the actual temperature when the relative humidity is high. If the relative humidity is low, we can feel much cooler than the actual temperature because our sweat evaporates easily, cooling us off.

3.Temperature • Energy from the sun heats air in the atmosphere, drives air movement, helps create seasons, and influences weather and climate • 70% of solar energy is absorbed by the atmosphere • Why is solar radiation intensity the highest near the equator and weakest near the poles? • How it strikes the surface of the Earth (angle) and distanced travelled

Seasons

Convection circulation

Terminology • Weather (“what we get”) • the state of the atmosphere with respect to wind, temperature, cloudiness, moisture, pressure, etc. • Climate (“what we expect”) • the composite or generally prevailing weather conditions of a region, as temperature, air pressure, humidity, precipitation, sunshine, cloudiness, and winds, throughout the year, averaged over a series of years.

Air Masses Warm Front Clouds/May produce light rain Cold Front Clouds/Can produce thunderstorms

High/Low Pressure Systemshigh pressure moves to low pressure high pressure- fair weather Low Pressure- clouds/precipitation

NC-warm air rises, vertical mixing/dilutes pollution. TI – resists vertical mixing + remains stable/cause smog/traps pollutants near ground (ex: mountain valleys) Normal conditions/thermal inversion

Large Scale Convective CellsHadley cell- creates high pressure (descends) Polar Cell- creates low pressure (Rises)ferrel cell- moves high to low

YouTube Search Powered by iBoss

Outdoor Air Pollution • Air pollutants • Gases and particulate material added to the atmosphere that can affect climate or harm people or other organisms. • Air Pollution • Release of air pollutants • Outdoor air pollution (ambient or environment air pollution)

Outdoor Air Pollution • Natural processes produce a great deal of the world’s air pollution exacerbated by human activity and land-use policies. • Winds • Dust storms • Volcanic eruptions • Particulate matter and gases (S02) • Sulfur dioxide reacts with water and oxygen (condensed fine droplets called aerosols) which reflects sunlight back into space causing a drop in temperature • Burning vegetation • “slash-and-burn” • C0 release into the atmosphere

Atmospheric Science and Air Pollution