Transcript Unit 3 “Human Footprint”

Unit 3
“Atmospheric Science & Air
Pollution”
Atmosphere
• Atmosphere – thin layer of gases that surround
the earth; composed of 5 sub layers
– 1. Troposphere – closest to the earth, has most
oxygen of any of 5
– 2. Stratosphere – Ozone predominantly found here
– 3. Mesosphere – Ionosphere (weakly charged ions)
located in upper portion
– 4. Thermosphere – increase in temperature;
uppermost portion of Ionosphere located here
– 5. Exosphere – interface between earth’s atmosphere
and space; very few gases
Atmosphere
Atmospheric Properties
• Composition of gases: 78% N, 21% O, 1% trace
gases
• As altitude increases, pressure ___________.
Why?
• As altitude increases (exception in
thermosphere), temperature ____________.
Why?
• As altitude increases, density ___________.
Why?
• http://video.nationalgeographic.com/video/101videos/weather-101-sci
Ozone Layer
• Found in the Stratosphere and is composed of O3
molecules
• Blocks UVA and UVB rays from reaching earth’s
surface
• In the latter part of the 20th century, due to the
use of products containing CFC’s, the Ozone Layer
was depleted
• In the 1990’s many governments banned the use
of CFC’s; as a result, the hole in the Ozone was
reduced
Ozone Layer Depletion
• Keeping Ozone Layer intact is important
because it keeps harmful UV rays from
reaching the earth’s surface thereby
preventing skin cancer
Weather and Climate
• Weather – day to day fluctuations in
temperature and precipitation
• Climate – average weather conditions from
year to year
• Whatever the conditions are in the
atmosphere, those conditions will affect
weather, and lastly climate
Air Masses and Pressure Systems
• Cold air mass = high pressure system
• Warm air mass = low pressure system
• As is the case with ocean currents, there are
horizontal and vertical air currents
• Vertical air currents are called Convection
Currents (hot air or fluid expands and is therefore
less dense than its cooler surroundings, thus it
rises; as it cools it contracts, becomes more
dense and sinks down creating something of a
rolling motion)
Air Masses and Pressure Systems
• Also, the ocean’s physical conditions
(temperature etc.) affect the physical
conditions of the atmosphere and vice/versa
• Evidence of how the ocean’s physical
conditions affect atmosphere/weather is the
occurrence of hurricanes (require warm ocean
water to develop)
• http://sciencelearn.org.nz/Contexts/H2O-Onthe-Go/Sci-Media/Video/Water-and-weather
Air Pollutants
• Primary Pollutants – emitted into the
troposphere already in a form that is harmful
to life in the biosphere
– Example
CFC’s
• Secondary Pollutants – result of primary
pollutants reacting with each other or other
substances in the atmosphere to form new
pollutants
– Example
Acid Rain
Air Pollutants
• Acid Rain – sulfur dioxide from coal burning
power plants combines with water vapor
• Smog – coal and/or oil soot is released into
the air
• Particulate pollution – small solid particles
released into the air as a result of industrial
processes; results in asthma and other
respiratory ailments
Mitigating Air Pollutants
• Just as the Clean Water Act was put in place to
protect the hydrosphere, the Clean Air Act
was put into effect beginning in the 1960’s to
protect the atmosphere
• The Clean Air Act of 1990 - intent was to
strengthen standards instituted in the 1970
version of the act; it also introduced an
emissions trading program for sulfur dioxide
(acid rain)
Market Based Incentives versus
Government Regulations
• Incentives = voluntary; if done properly
provide an economic incentive to industry to
“clean up their act”
• Regulations = involuntary; government
requires industry to comply with regulations,
sometimes causing them to become less
competitive
• Which is better? It depends on the variables
involved!
Climate/Atmosphere/Meteorology
Summary
• https://www.youtube.com/watch?v=lrPS2HiY
Vp8&index=13&list=PLIDao9d2upp5Q3ffAXK0
3OcjfLQHUGK3b