Envi Sci- Bastin
major gases in atmosphere
nitrogen, 78%
oxygen, 21%
argon, 1%
carbon dioxide, 0.04%
troposphere
75% of mass of earth’s air
where weather occurs (most clouds here)
temperature down as altitude goes up
stratosphere
contains ozone layer
air here is “thinner” than troposphere
temperature up as altitude goes up
thermosphere/ionosphere
to lower limits of space
feels cold b/c molecules spread far apart
exosphere
outer limits of atmosphere
structure of atmosphere (lowest to highest)
troposphere, stratosphere, mesosphere, thermosphere, exosphere
weather
state of the atmosphere at a particular time and place
climate
average conditions
classified by temperature & precipitation
influenced by latitude, elevation
how latitude affects climate
height of noon day sun
length of day (12hr days year-round near equator; long summer/short winter days at poles)
adiabatic lapse rate
rate at which temperature drops with elevation. temp. decrease of 21°F/1000 ft.
air ___ as elevation increases
cools
effect of elevation on precipitation
as warm air rises up /west side of mountain, it cools, reaches saturation, and clouds form
moisture precipitates out
air descends down leeward/east side of mountain, warms, humidity decreases (why deserts are east of mountains)
humidity
amount of water in air
relative humidity
how close air is to saturation
100d°, can’t hold more water (tropics)
5d°, desert- warm air holds more water than cold air
terrain and albedo
surface reflectivity
surfaces easily heated
asphalt- absorbs, doesn’t reflect (low albedo)
increased temp. over cities called “heat islands”
sand
surfaces slowly heated
snow- extremely reflective (high albedo)
water, forests
primary factors affecting atmospheric circulation
earth’s rotation & differential heating of earth’s surface
atmospheric circulation results in:
wind patterns, latitudinal belts of high and low air pressure
coriolis effect
earth’s rotation on its axis
wind
more solar radiation at equator- sun heats atmosphere unevenly
differences in temp. cause differences in pressure, which cause wind
direction based on where it comes from (ex. east to west = westerly)
air pressure
caused by gravity (weight of air)
measured in inches of mercury (barometer)
pressure greater near surface of earth than high up due to weight of air
low pressure areas
rising air masses
unsettled weather (rain)
winds (cyclones) move counter-clockwise in n. hemisphere & inverse in s. hemisphere
at equator & between 50-60° north and south latitudes
high pressure areas
descending air masses
stable, dry conditions (warmer)
winds (anticyclones) move clockwise in n. hemisphere & inverse in s. hemisphere
found between 25-30° north & south latitudes
trade winds
steady winds from equator to 30° north/south of equator
horse latitudes
30°+ north/south of equator, high pressure areas where deserts are found
doldrums
areas with little wind at equator
three major air pressure zones
doldrums, trade winds, horse latitudes
fronts
where two air masses meet
warm front
warm air mass rises over cooler, light rain
cold front
cold air pushes under warmer, warm air rises. clouds & rain form.
stationary front
air masses don’t move
occluded front
two moving fronts meet
how clouds are formed
temperature high, more water evaporates. water vapour present in the air condenses to form tiny droplets of water that become clouds.
types of clouds
high level (prefix cir)- circus clouds
mid level (prefix alto)- alto cumulus
low level (prefix strat)- stratus
heavy rain (prefix nimbo)
thunderstorms
air rises rapidly
lightning
buildup of opposite charges within a cloud that meet
thunder
due to intense heating of air by lightning
air expands with supersonic speed producing “slap”
tornadoes
develop from thunderstorms
low pressure “eye” surrounded by spinning funnel of 300mph winds
tornado alley= oklahoma to illinois
hurricanes (typhoons)
begin over warm tropical oceans, fueled by evaporating ocean water. die out when over land.
more frequent with global warming (oceans/air warm, more water evaporate, more severe hurricanes)
monsoons
winds which reverse seasonally, mostly over coastal areas
land heats/cools faster than oceans- hot air rising from land creates low pressure system, rising air replaced by cooler moist air blowing in from ocean, precipitation forms as moist air raises
el niño southern oscillation (ENSO) conditions
occurs in tropical pacific ocean off south american coast near xmas every 2-7 years
trade winds weaken or reverse and blow east across pacific (from indonesia to south america), warm surface water piles up in eastern pacific- now higher at peru than indonesia, warm ocean water off south america decreases nutrient upwelling (bad anchovy fishing). warmer water = more rain in peru
typical conditions
trade winds blow west across tropical pacific (south america to indonesia), warm surface water piles up in western pacific, cooler ocean water off south america increases nutrient upwelling (better anchovy fishing).
la niña
opposite of el niño conditions/events. results in cooler temperatures and less rainfall in the americas.
warm periods (interglacial)
most ice melts
cool periods (glacial events/ice ages)
polar ice/glaciers over continents
sea levels drop
how greenhouse effect works
short w.l. radiation from sun travels through atmosphere to earth
short w.l. radiation absorbed by earth’s surface and readmitted as l.w. radiation
atmospheric gases absorb & reeemit l.w. radiation (infrared/heat) back to earth
gases act like glass sides of a greenhouse
causes of greenhouse effect
primarily from release of co2 and other greenhouse gases from burning of fossil fuels
effects of greenhouse effect
sea levels change, ocean acidification, shift in climate of many regions, species extinctions, etc.
positive feedback loop
intensifies effects (snow in arctic melts as it heats, less sunlight reflected, more heat retained)
negative feedback loop
counteracts effect (more water evaporates, more clouds form, sunlight prevented from reaching earth)
paris agreement
pledged to reduce emissions to limit global warming to below 2°C (aim for 1.5°C)
montreal protocol
pledged to reduce CFC emissions, many developed nations didn’t want to partake
solutions to greenhouse effect problems
reduce use of fossil fuels (alternative sources, economic incentives)
pump co2 underground and use areas previously containing natural gas
education
ozone/o3
measured in dobson units
pollutant in troposphere (component of smog)
colorless, secondary pollutant with slightly sweet odor. strong oxidant- cracks rubber, kills plants, stings eyes, lung damage
ozone layer
in stratosphere
an essential shield against UV radiation
damaged by CFC’s
CFC’s
last 75-140yrs in stratosphere
destroys o3 (see equation)
effects of ozone depletion
increase in skin cancer & cataracts, decreased growth of plants & plankton
major greenhouse gases
CFC’s, NO, Methane, CO2
solutions to ozone depletion
reduce/stop using CFC’s, stay out of sun/wear sunscreen, global summits
typical pH of rain
5.6
pH of acid rain
below 5.6
primary pollutants
emitted directly into air.
sulfur dioxide (SO2), nitrogen oxides (NOx), carbon monoxide (CO), hydrocarbons (HC), particles, particulates
formation of acid rain
primary pollutants mix w/water vapor in atmosphere and form secondary pollutants
SO2 to sulfiric acid- H2SO4 & sulfate salts
NOx to nitric acid- HNO3 & nitrate salts
precipitate out of atmosphere as rain, snow, fog, or dry particulates.
why acid rain occurs on regional scale
most pollution in canada & eastern u.s. from power plants in U.S. east of mississippi river. carried by winds for hundreds of miles.
why taller smokestacks ineffective
sends pollution downwind- increase the distance these pollutants travel in the atmosphere and harm air quality and the environment in downwind communities.
what determines sensitivity of a region
buffering capacity- ex. thick soils and limestone more resistant to changes in pH, lakes in eastern U.S. not resistant due to no more buffering capacity
effects of acid rain
vegetation- weakens trees/plants by damaging protective “cuticle” and makes more susceptible to disease or pests. acids affect soil nutrient levels
aquatic systems- acidification of thousands of lakes in northeastern u.s. & canada. fish suffocate as metals (ex. aluminum) leaching into water damage gills. eggs perish because they are porous.
buildings- acid eats away surface. ex, limestone cathedrals in europe & sphinx,
humans- damages our food supply and our environment.
solutions to acid rain problem
stop burning high sulfur coal (remove sulfur prior to burning), pollution control devices (wet scrubber), treat acid lakes with limestone (CaCO3)- expensive and must be repeated so not super efficient.
coal gasification
turn coal into gas and remove sulfur
wet scrubber
treat exhaust gas with water/lime mixture to remove sulfur
electrostatic precipitation
installed on smokestack. electrical current removes particulates from exhaust gas (laser tag)
baghouse filters
installed on smokestack. like large vacuum bag, filtering particulates out before they escape into the air.
sulfur dioxide (SO2)
from coal burning power plants or naturally from volcanos & sea spray
colorless, odorless gas
leads to acid rain
nitrogen oxides (NOx)
from power plants and auto exhaust
nitric oxide (NO)- color/odor free
nitrogen dioxide (NO2)- yellow-brown, gives smog color, irritates eyes, increases susceptibility to infection
hydrocarbons (HC)
contain carbon & hydrogen
carbon monoxide (CO)
colorless, odorless, extremely toxic- binds to hemoglobin in blood (taken up 250x faster than oxygen) and suffocates you at the cellular level.
particles
suspended in air, dangerous in high concentrations
particulates
particles suspended in air
smoke/dust (can be natural)- dangerous in high concentrations, smoke inhalation
fine particles become embedded in lungs and cause cancer (ex. asbestos- historically in brake pads & old insulation)
secondary pollutants
produced by reactions between primary pollutants & atmospheric compounds
ozone (o2), acid rain, particulates
stationary air pollution
point: from fixed point
fugitive: open areas
mobile air pollution
move while yielding emmissions, ex. cars.
industrial smog
sulfur dioxide, particulates
present during winter in cities burning coal, mainly in developing countries nowadays
photochemical smog
formed in sunlight- so happens later in the day
ozone forms later in the day after levels of NO2 & NO build up.
influence of precipitation on climate/smog
rainy areas typically have less smog- rain cleans air of pollutants
solutions to smog (stationary sources)
emissions trading and banking (limited emissions credits lets the market solve the problem), control devices on smokestacks
solutions to smog (mobile sources)
catalytic converted on auto exhaust- uses platiunum catalyst to increase reation of NO to N2 and CO to CO2. reduces NOx & CO2 emissions
smog checks
reformulate gasoline to lower emissions
switch to electric vehicles
air quality index
a daily index used to tell how clean air is (scale of 0-500)
indoor air pollution issues
concentration of pollutants often greater indoors than out (lack of ventilation)
health risks magnified as people spend 70-98% of their time inside