The Atmosphere, Climate, and Global

WarmingBasic Atmospheric Composition

-Composed of gas molecules held close to Earthby gravity and thermal movement of molecules.

-Major gases in the atmosphere:Nitrogen (78%)

Oxygen (21%)Argon (0.9%)Carbon Dioxide (0.3%)

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

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.

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.

Atmospheric Profile

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.

Atmospheric Profile

Characteristics of the AtmosphereAir masses are usually characterized by threequalities. 1) Atmospheric pressure:

The force per unit area of the atmosphere pushing down on the Earth.Pressure decreases as altitude increases because there isless 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

2) Temperature:Measured in Fahrenheit, Celsius, or KelvinMost measurements are taken in Celsius, exceptin the U.S., where the Fahrenheit scale is still inuse, (at least by the public and on T.V.)

Temperature is the measure of the amount of kinetic energy within the atmosphere. The higher the temperature, the more energy contained.

The conversion from F to C:Co = 5/9(Fo – 32)

Temperature Scale Relationships

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%

Circulation of the AtmosphereAtmospheric circulation results primarily from theEarth’s rotation and differential heating of Earth’ssurface 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.

Generalized Circulation of the Atmosphere

Belts of high pressure develop near 25o

to 30o north and south latitude.

The pervasive high pressure, and theresulting low precipitation cause Earth’s major deserts to be located at these latitudes.

The poles are also subject to high pressureareas, and therefore actually get little realprecipitation.

Climate-Refers to the characteristic atmosphericconditions for a region of Earth.

-Implies long periods of time, such asyears or decades.

Climate is based upon temperature and precipitation.

Shorter term events are called weatherconditions, and are measured in daysweeks, or sometimes months.

Classification of Climate by LatitudeThe simplest way to categorize climates is by their latitude on Earth.

TropicalSubtropical

MidlatitudinalSub Arctic

Arctic

Other Categories of ClimateOther categories include:

Humid ContinentalMediterranean

MonsoonTropical wet-dry

It is important to recognize the fact that climateis the key driver in determining what type of biological systems will prevail in an area.

MicroclimateLocalized areas may have climate conditions different than a region.May be caused by something like a lake or river.

Microclimate can also extend down to very smallareas, such as under a log or rock.

Ex: Areas around Great Lakes, or an oasis in a desert.

Air Pollution1) Sources of Air Pollution

Point Sources: emit from one or morecontrollable sites, such as smoke stacks Fugitive Sources: emit pollution from open areas exposed to wind. Ex: burning for agriculture, open mines whichcreate dust, construction sitesMobile Sources: emit pollution as they move.EX: automobiles, airplanes

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

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

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

Photochemical smog in the LA basin

Photochemical smog in Mexico City

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

Particulate Matter: (PM 10 and PM 2.5)-PM 10 is made of particles less than 10 um indiameter.PM is made of dust particles from soil, smoke,soot, heavy metals, asbestos, etc…

PM 2.5 is very fine particulate matter, less than2.5 um in diameter. High concern, because very fine PM is taken deepInto lungs, and can sometimes cross into blood. EX: nitrates, sulfates

Urban Air PollutionIn 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 urbanarea. Concentrations of pollutants can get very high, and stay high.

Mexico City

Los Angeles

Pollution ControlsSulfur 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 andcrushed limestone (CaCO3) Calcium sulfite (CaSO3) is formed, removing thesulfur from the gas

Flue Gas Scrubbing

Pollution Controls: Automobiles

Since the mid-70’s, automobiles have run onunleaded gasoline, reducing the lead pollution. All automobiles are supposed to have a catalyticconverter, which reduces hydrocarbon andcarbon monoxide emissions.Pollution controls are supposed to be checked in the inspection process.

Reformulated gasoline has fewer pollutants,and burns cleaner, making less pollution.

Pollution Controls: ParticulatesPoint source polluters have reduced their pollutiongreatly in the past 50 years. -settling chambers allow particulates to be removed Ex: ash and dust from power plantsParticulates 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.

Indoor Air PollutionFor many pollutants, indoor concentrations aregreater than outdoor concentrations.

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 moldsRadon gasPesticides of all kindsAsbestosFormaldehyde (from glues and plastics)

VOC’s of all types (from paint to spray cans)Carbon Monoxide (from poorly functioning heaters)

Sick Building SyndromeThere have been cases of buildings which hadto be evacuated and or torn down because ofpoor indoor air quality.

There are two types:1)Buildings with identifiable problems, such asmold. These can be fixed and the buildings re-occupied safely. 2) SBS, where the causes of symptoms are notidentifiable. Chronic health problems can effect a large number of workers.

Radon GasColorless, odorless gas, naturally occurring Seeps into basements through cracks/openingsCan be held in the materials used to build a home

Rocks, cement blocks, etc..Radon causes damage because it is radioactive,and is believed to cause lung cancer.Radon can be eliminated from a home by havinggood ventilation in the basement, and by monitoring suspect homes for high levels

CH25: Ozone Layer and Ozone DepletionOzone is a colorless, odorless gas, with the formula of O3

Ozone is formed by the addition of a free oxygenatom to an oxygen molecule. (25.3)

The Importance of Ozone

Ozone acts as a screen for UV radiation in theStratosphere.

99% of incomingSolar UV is screenedby the ozonelayer.Without the ozonelayer, life on Earthwould not be possible.

Destruction of Stratospheric Ozone

Measurements of ozone have been going downsince measurements first took place.

Ozone DepletionIt is widely held that man-made products, especially chlorofluorocarbons (CFC’s), areresponsible for the lowering amounts of ozone.

Other products, such as Methyl Bromide andNOx have also been shown to be potent ozone depleters

The Effects of Less Ozone

Increased UV means increases in skin cancerLower crop yields, due to over exposure to UVLower photosynthetic rates in the oceans

Coral reef die-outs due to UV bleaching

Fewer Frost DaysAnnual Number of Frost Days

1948-1999

All U.S. = - 0.8%NOAA

Projected Precipitation Projected Precipitation ChangesChanges

Changes in USDA Hardiness Zones

1990 Map 2006 Map

USDA Arbor Day