Atmospheric Science and Air Pollution - Employee ….ppt

Lecture Outlines
Chapter 17
Environment:The Science behind the Stories
4th Edition
Withgott/Brennan
This lecture will help you understand:
The Earth’s atmosphere
Outdoor pollution and solutions
Stratospheric ozone depletion
Acidic deposition and consequences
Indoor air pollution and solutions
Central Case: . and its sister cities struggle for a breath of clean air
Vehicles caused smog in Los Angeles from 1970s to 1990s
Policies and technologies improved its air qualities
But its “sister cities” are not as clean
3,600/month die in Tehran from air pollution
Old cars use cheap gas
Topography, immigration, etc.
Central Case: Charging toward cleaner air in London*
London has had bad air pollution for centuries that has killed thousands
Today, smog from traffic is a problem
The “congestion-charging” program charges drivers to drive into central London during the week
Congestion decreased, fewer accidents occurred and the air became cleaner
The atmosphere*
Atmosphere = the thin layer of gases that surrounds Earth
Absorbs radiation and moderates climate
Transports and recycles water and nutrients
78% nitrogen gas, 21% oxygen gas, 1% other gases
Its four layers differ in temperature, density position
Minute concentrations of permanent (remain at stable concentrations) and variable gases (varying concentrations)
Human activity is changing the amounts of some gases
The atmosphere’position
The first two layers of the atmosphere*
Troposphere = bottommost layer
Air for breathing, weather
Temperature declines with altitude
Relative humidity
Tropopause = limits mixing between troposphere and the layer above it
Stratosphere = 11-50 km (7-31 mi) above sea level
Drier and less dense, with little vertical mixing
Colder in its lower regions
Contains UV radiation-blocking ozone, 17-30 km (10-19 mi) above sea level
The two highest levels of the atmosphere
Mesosphere = 50-80 km (31-56 mi) above sea level
Extremely low air pressure
Temperatures decrease with altitude
The