Download 12-4 ch18

 Warm-up: (3-2-17)
*Alligator article/rubric out for stamp!
 1. A (lower, higher) LD50 is more toxic. Explain your answer.
 2. Give an example of a persistent chemical. What makes it so persistent?
 3. A major cause of a reduced human life span today is…
 4. A person experiencing dizziness after using a strong household cleaner is showing (acute, chronic) effect.
 5. T/F. A virus can be a carcinogen.
 Chapter 18-1
 Atmosphere
 Goals for today:
 Explain how lichen is like a canary
 List the layers of the atmosphere and its composition
 Describe the pros and cons of ozone in our atmosphere
 Explain the effects of carbon oxides
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Lichen Like a Canary?
 What is lichen?
 What type of relationship exists between these two organisms?
 Why are they like a canary?
 Do lichen have roots?
 So how do they take in the nutrients they need to grow?
 Some lichen species are sensitive to specific air-polluting chemicals.
 After Chernobyl, more than 70,000 reindeer had to be killed because they ate highly radioactive lichens.
 Lichens can help us track pollution to its source because they are:
 Widespread
 long-lived
 anchored in place
 STRUCTURE AND SCIENCE OF THE ATMOSPHERE
 The atmosphere consists of several layers with different temperatures, pressures, and compositions.
 What are the 4 main gases in air (excluding water vapor)?
 78% nitrogen
 21% oxygen
 1% argon
 < .1% carbon dioxide
 Name the four layers of the atmosphere…
 Troposphere
 Stratosphere
 Mesosphere
 Thermosphere
 Troposphere
 Troposphere:
 layer closest to the Earth's surface
 extending up to about 10-15 km above the Earth's surface.
 contains 75% of the atmosphere's mass
 wider at the equator than at the poles.
 Temp. and pressure drop as you go up
 Tropopause
 Very top of the troposphere
 Temperature reaches a (stable) minimum
 a "cold trap" because rising water vapor can’t go higher because it changes into ice
 What causes the production of wind?
 Warm air from Earth's surface rises and cold air above it rushes in to replace it.
 Most clouds/weather occur in the __________.
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Stratosphere
Above the troposphere
extends from about 15 to 50 km above the Earth's surface
Temp. increases with altitude because of absorption of sunlight by ozone (ozone layer)
opposite of the temp. situation in the troposphere
Ozone Layer
Blocks out 95% of UV radiation
 Allows life to exist
 Prevents sunburn/cancer of skin
 Prevents oxygen in troposphere from converting into toxic ozone
Mesosphere
Above the stratosphere
Extending from 50 to 80 km above the Earth's surface
A cold layer where the temp. decreases with increasing altitude
Where meteors burn up
Thermosphere
Extends from 80 km – 320 km
Temp. is hot
However, the thermosphere would actually feel very cold to us because so few molecules will hit our skin and
transfer enough energy to cause appreciable heat
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 What does our atmosphere do?
 Two main natural processes
 Greenhouse effect – keeping the planet warm through absorbing long wave radiation from the planet
(water, CO2, CH4)
 Ozone shield – blocking unwanted UV radiation
 Major Air Pollutants
 Ozone (O3):
 Is a highly reactive gas that is a major component of photochemical smog.
 It can
• Cause and aggravate respiratory illness.
• Can aggravate heart disease.
• Damage plants, rubber in tires, fabrics, and paints.
 Good to have in stratosphere, bad in troposphere
 Major Air Pollutants
 Carbon oxides:
 Carbon monoxide (CO) is a highly toxic gas that forms during the incomplete combustion of carboncontaining materials.
 93% of carbon dioxide (CO2) in the troposphere occurs as a result of the carbon cycle.
 7% of CO2 in the troposphere occurs as a result of human activities (mostly burning fossil fuels).
• CO2 is not regulated as a pollutant under the U.S. Clean Air Act.
 Check for Understanding:
 1. List the layers of the atmosphere from the inner most to outer layer.
 2. The atmosphere is divided into spherical layers based upon the _____.
 3. The atmospheric layer containing 75% of the mass of earth's air is the _____
 4. How is lichen like a canary?