The Atmosphere, Climate, and Global Warming

1. The Atmosphere, Climate, and Global Warming Basic Atmospheric Composition -Composed of gas molecules held close to Earth by gravity and thermal movement of molecules. -Major gases in the atmosphere: Nitrogen (78%) Oxygen (21%) Argon (0.9%) Carbon Dioxide (0.3%)

2. Other gases (and things) found in the atmosphere: Most are found in trace amounts, and may vary in concentration over time, and area. -methane -ozone -hydrogen sulfide -hydrocarbons -oxides of Nitrogen and Sulfur -chlorofluorocarbons (CFC’s) -all kinds of particulates (aerosols) -water vapor

3. The Atmosphere as a Dynamic System -The atmosphere is a dynamic, ever changing system. -Air masses with different characteristics move, and produce weather and climate. -Movement is caused by differing temperatures day/night and regionally, energy from living organisms (think rain forest), by human industrial and agricultural activities. -The atmosphere has been modulated primarily by biological activity for 3.6 billion years.

4. Important Atmospheric Layers -there are two layers of the atmosphere which are the most important to our environment. 1)Troposphere (where weather occurs) -lower 10 to 12 km -temperature decreases with elevation, 17C at surface to –60C at 12km in elevation -at the top of the troposphere, the tropopause is a boundary with a constant temp. of –60C. -the tropopause causes condensation of water vapor, and keeps it within the troposphere.

5. Atmospheric Profile

6. 2) Stratosphere • reaches from the top of the tropopause to about • 50 km in elevation. -contains the ozone layer, which has its greatest concentration at 25-30 km above the Earth. -Ozone (O3) is responsible for protecting life from the effects of ultraviolet radiation from the Sun.

7. Atmospheric Profile

9. Characteristics of the Atmosphere Air masses are usually characterized by three qualities. 1) Atmospheric pressure: The force per unit area of the atmosphere pushing down on the Earth. Pressure decreases as altitude increases because there is less atmosphere pushing down from above. Measured in N/m2 (Newtons per square meter) or in lb./in2 (pounds per square inch) Sea Level: 105 N/m2 or 14.7 lb./in2

10. 2) Temperature: Measured in Fahrenheit, Celsius, or Kelvin Most measurements are taken in Celsius, except in the U.S., where the Fahrenheit scale is still in use, (at least by the public and on T.V.) The conversion from F to C: Co = 5/9(Fo – 32) Temperature is the measure of the amount of kinetic energy within the atmosphere. The higher the temperature, the more energy contained.

11. Temperature Scale Relationships

12. 3) Moisture Content: Air masses are usually characterized by their water vapor content. Often referred to as humidity, the amount of water vapor that can be carried is related to the temperature and pressure of the air. Relative humidity is a measure of how much moisture the air can carry. Air that can carry no more water vapor is called saturated, and the relative humidity is 100%

13. Circulation of the Atmosphere Atmospheric circulation results primarily from the Earth’s rotation and differential heating of Earth’s surface and the atmosphere. This circulation produces global patterns that include prevailing winds and latitudinal belts of high and low air pressure from the equator to the poles. Rising columns of air at the equator produce low pressure areas, producing precipitation.

14. Generalized Circulation of the Atmosphere

15. Belts of high pressure develop near 25o to 30o north and south latitude. The pervasive high pressure, and the resulting low precipitation cause Earth’s major deserts to be located at these latitudes. The poles are also subject to high pressure areas, and therefore actually get little real precipitation.

16. Climate -Refers to the characteristic atmospheric conditions for a region of Earth. Climate is based upon temperature and precipitation. -Implies long periods of time, such as years or decades. Shorter term events are called weather conditions, and are measured in days weeks, or sometimes months.

17. Classification of Climate by Latitude The simplest way to categorize climates is by their latitude on Earth. Tropical Subtropical Midlatitudinal Sub Arctic Arctic

18. Other Categories of Climate Other categories include: Humid Continental Mediterranean Monsoon Tropical wet-dry It is important to recognize the fact that climate is the key driver in determining what type of biological systems will prevail in an area.

20. Microclimate Localized areas may have climate conditions different than a region. May be caused by something like a lake or river. Ex: Areas around Great Lakes, or an oasis in a desert. Microclimate can also extend down to very small areas, such as under a log or rock.

21. Air Pollution 1) Sources of Air Pollution Point Sources: emit from one or more controllable sites, such as smoke stacks Fugitive Sources: emit pollution from open areas exposed to wind. Ex: burning for agriculture, open mines which create dust, construction sites Mobile Sources: emit pollution as they move. EX: automobiles, airplanes

22. Major Air Pollutants Ozone (03): strong irritant, aggravates asthma, causes plants to die back or crops to be reduced. Cracks paint, rubber, causes colors to fade.

24. Sulfur Dioxide (S02): Increase in respiratory disease, bleaching and decay in plants, dissolves Metal and stone. -When mixed with water in air, creates acid rain

28. Nitrogen Oxides: (NOx) aggravates respiratory problems, also a cause of acid rain, causes bleaching of colors. -Responsible for “photochemical smog”, reacts sunlight to form a brown cloud at ground level

29. Photochemical smog in the LA basin

30. Photochemical smog in Mexico City

33. Volatile Organic Compounds (VOC’s): Hydrocarbon compounds from solvents, fuels, paints, etc.. A major source of VOC’s are automobiles and gasoline vapors Also a component of photochemical smog

37. Particulate Matter: (PM 10 and PM 2.5) -PM 10 is made of particles less than 10 um in diameter. PM is made of dust particles from soil, smoke, soot, heavy metals, asbestos, etc… PM 2.5 is very fine particulate matter, less than 2.5 um in diameter. High concern, because very fine PM is taken deep Into lungs, and can sometimes cross into blood. EX: nitrates, sulfates

38. Urban Air Pollution In urban areas, especially if air is trapped, an inversion may develop. An inversion happens when air is not allowed to circulate, and carry pollution away from the urban area. Concentrations of pollutants can get very high, and stay high.

39. Los Angeles Mexico City

42. Pollution Controls Sulfur Dioxide: -switch to low sulfur coal -coal gasification (converts coal to gas, which is low in sulfur) -scrubbing flue gasses: remove SO2 via a “filter” Gasses are passed through a slurry of water and crushed limestone (CaCO3) Calcium sulfite (CaSO3)is formed, removing the sulfur from the gas

43. Flue Gas Scrubbing

44. Pollution Controls: Automobiles Since the mid-70’s, automobiles have run on unleaded gasoline, reducing the lead pollution. All automobiles are supposed to have a catalytic converter, which reduces hydrocarbon and carbon monoxide emissions. Pollution controls are supposed to be checked in the inspection process. Reformulated gasoline has fewer pollutants, and burns cleaner, making less pollution.

45. Pollution Controls: Particulates Point source polluters have reduced their pollution greatly in the past 50 years. -settling chambers allow particulates to be removed Ex: ash and dust from power plants Particulates from fugitive sources must be controlled at the site of creation. (covers, grass, wetting with water, etc..) Diesel engines are being closely regulated to lower the amount of particulates that they produce.

48. Indoor Air Pollution For many pollutants, indoor concentrations are greater than outdoor concentrations.

49. The reason indoor pollution is greater is because of the lack of good ventilation, and the need to make houses more energy efficient. Some common indoor pollutants: Second Hand tobacco smoke Various molds Radon gas Pesticides of all kinds Asbestos Formaldehyde (from glues and plastics) VOC’s of all types (from paint to spray cans) Carbon Monoxide (from poorly functioning heaters)

50. Sick Building Syndrome There have been cases of buildings which had to be evacuated and or torn down because of poor indoor air quality. • There are two types: • Buildings with identifiable problems, such as • mold. These can be fixed and the buildings • re-occupied safely. 2) SBS, where the causes of symptoms are not identifiable. Chronic health problems can effect a large number of workers.