Envi Sci Atmosphere Unit

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