GEOG 108 Midterm 2
N2 - how is this removed from atmosphere and deposited at earth
N2 is removed from atmosphere and deposited at earth's surface by specialized bacteria that can fix N2 gas, as well as by way of lightning through precipitation
chemical layers - ozone layer
- 10-50 km above earth - highest conc of ozone gas here is at 25km - without this layer, life could not exist
mesosphere
50-90 km above earth - very thin air that can get very cold - temps decrease with altitude, top of this layer -90 C
significance of 70% in shortwave and longwave
70% shortwave is absorbed by earth's surface and atmosphere, and 70% longwave leaves earth i.e. is lost to space
2nd most important greenhouse gas, what percent is it responsible for
CH4 (methane) - responsible for 18% of greenhouse effect recently
ionosphere and the 3 D E F layers
D and E layers only work in daytime and distort radio waves because they absorb them, so increasing the strength of waves is needed, so F layer is used at night to transport radio waves because less distortion due to less absorption of the radio waves
what two main gases make up dry atmosphere
N2 and O2 - 78% is N2, 21% O2 ---- make up 99% of dry atmosphere!
global warming: since 1990, how much has earth heated up?
about 0.3-0.6 C since 1990
main power source for heating is what? but, what is another importance one?
insolation! but earth receives lots of longwave radiation mainly from greenhouse effect that is also very important.
most common type thermometer, when heat added vs cooled, type types
liquid-in-glass thermometer! glass tube with small uniform bore and a bulb at one end filled with suitable liquid which responds to addition or loss of heat from outside enviro by changing volume - when heat added = liquid expands and moves up - when cooled = liquid contracts and moves down - two types: minimum and maximum thermometers
annual temp range
max month temp minus mix month temp
daily temp range
max temp minus min temp
if radiation loss of emission exceeds absorption
object cools down
aerosols - most numerous where, and greater in lower atmosphere why
over cities, seacoasts, and over areas of non-vegetated soil - greater in lower atmosphere because density of air increases as you approach earth's surface
monthly mean temp
summing all daily means for the month then diving by number of days in the month
stratosphere
- 20-50 km above earth - 20% atmosphere mass - minimal weather and vertical mixing here - occasionally top of thunderstorm may breach bottom of stratosphere - temp increases with altitude because of concentration of ozone gas absorbing UV radiation creating heat - temp ranges from -57 C to 0 C at layer's upper boundary
annual global radiation cascades----global SHORTWAVE radiation cascade
- 25 units of energy is reflected or scattered back to space by clouds and particles - 20 units is absorbed by clouds, gases, and particles (mostly occurs in troposphere) - of remaining 55 units, ~50 units reach earth's surface
chemical layers - ionosphere
- 60 to 400 km above earth - thick layer with positive charged ions due to solar radiation (lots of free electrons) - transport radio waves in this layer across long distances, best works at night*
troposphere
- 8-16 km above earth, average 11km (thicker at equator, thinner at poles) - thicker during summer due to expansion of atmosphere and presence of warm updrafts pushing upper boundary to higher altitude - holds 80% of atmosphere mass because very dense - temp decreases as you go up in troposphere (drops 6.5 C per 1000 m) - average temp -57 C at top of troposphere - pressure decreases as you go up - most important thermal layer because this is where our weather occurs - vertical mixing most in summer when intense solar radiation generates convective thermals--can generate cumulus and cumulonimbus clouds -
thermosphere
- 90+ km above earth - very hot--1200 C!!!! because of absorption of intense solar radiation by O2 - temp increases with altitude - while these temps seems extreme, amount of heat capacity in low-density air is very small because air in thermosphere is extremely thin with individual gas molecules being separated!
precipitation is efficient in cleaning atmosphere of aerosols in what 2 ways
- aerosols act as nucleus of raindrops and snow crystals - falling rain droplets and snow crystals capture many particles by collision during their path to ground
water vapour - H2O. concentration varies where and what 2 reasons why, high conc where, low conc where
- concentration varies dramatically in lower atmosphere both spatially and temporally - two reasons why: warmer air has more internal heat energy increasing evaporation of liquid-->vapour, and air located over water bodies is supplied with more moisture because of evaporation - high conc found near equator over oceans and humid tropical rain forests - lowest conc or even 0% water vapour found in cold polar areas and subtropical continental deserts
early atmosphere
- dominated mostly by CO2, N2, H2O (but there was also CO, NH3, CH4, SO2, S2) - 4.4-4.0 billion years ago - most of early atmosphere was created in first 1 million years - this atmosphere was 10-20x denser atmosphere than today's due to large amounts of evaporated air - dominant features and processes here: lighter gases like H and He escaped to space very early on ;all weather was held in atmosphere as vapour because of high temp
earth space bound emission - what wavelength band, what length of emission
- earth's emission spectrum is in infrared band and wavelength of max emission is at 10 micrometers
fourth most abundant gas in atmosphere - CO2. exchanged through what? enhances what 2 things?
- exchanged through photosynthesis and respiration - greenhouse gas enhancing greenhouse effect (natural process providing additional heat energy to earth and lower atmosphere by absorbing longwave radiation) - enhances global warming (additional heat produced when various greenhouse gases absorb and remit outgoing long wave radiation)
chemical layers - homosphere
- extends from earth's surface to 80km - uniform mix of principal gases: N, O, Ar, CO2
ozone - O3. found in what 2 places, decreasing why, seasonal depletions where
- found in 2 places: most in stratosphere (97%) at 10-50 km above earth, and in/around cities (created as byproduct of human created photochemical smog...toxic to organisms) - protects life from UV rays, without this life could not survive - decreasing in stratosphere in recent years due to buildup of artificially created CFCs - seasonal depletion of ozone over Antarctica since 1970s, as well as 3-4% decrease in zone from 65 N-65 S
chemical layers - heterosphere
- gases are concentrated at distinct altitudes within the layer--heaviest gas (N) is concentrated at bottom, then O above that, then He, then H which is lightest is on top
rayleigh scattering
- insolation interacts with gas molecules at height of about 10 km in atmosphere - does not influence wavelengths uniformly...more effective with UV and shorter wavelengths (so mainly redirects blue wavelengths when the sun is well above horizon) - without RS, daylight sky would be black - RS does not occur on moon because atmosphere is too thin - responsible for orange and red skies seen BEFORE sunset or after sunset (blue wavelengths have to travel long distance when sun is at low angle, and when reaches observer its mostly all scattered out so now red/orange wavelengths are seen)
longwave output more evenly spread out than shortwave, this suggests what processes occur to redistribute short wave energy?
- longwave output from earth tends to be more evenly spread out than shortwave input... SO this suggests after the radiation is absorbed by earth and atmosphere, some of the energy is redistributed about the planet by other mechanisms: 1. greenhouse effect and 2. transfer of heat energy by horizontal circulation of atmosphere and ocean waters
maximum thermometer
- measures highest daily temps - uses mercury as liquid because freezing point is -39 C so this cannot be used in mix thermometers - vertical thermometer - reservoir bulb connected to tube that mercury extends up shaft when temp increases; constriction is too narrow to allow mercury to flow back into bulb when cooling occurs so it only measures max temps!
minimum thermometer
- measures lowest daily temps - uses alcohol in the glass tube because of low freezing point -218 C - horizontal thermometer to stop gravity from moving index slider
what natural and human processes influence transparency of atmosphere
- natural processes: cloud development, vegetation fires, sulphide emissions from marine plankton, wind transported dust, volcanic eruptions e.g. mount Pinatubo erupting --- took 3 years to dissipate! - human processes: gases and aerosols released into atmosphere from human activities... biomass burning, FF burning, vehicles
geographical imbalance of net radiation - where is the net radiation positive, and where negative
- net radiation more positive in tropics and subtropics (0-35 N&S) due to increased shortwave - net radiation more negative in middle and high latitudes (35-90 N&S) due to increased outgoing longwave and atmospheric circulation and ocean currents transferring amounts of latent and sensible heat from topics to higher lats
isothermal layers
- tropopause (where jet streams occur), stratopause, mesopause - transition zone where air temp does not change with altitude for distance of 9km
CO2 - how much have we increased this in 300 years
- we have increasing CO2 43% in last 300 years due to human activities like deforestation, burning FF, and conversion of prairie, woodland, and forested ecosystems to less productive ag systems (natural ecosystems can store 20-100x more CO2 than agricultural systems - before 1700, CO2 was 280 ppm, 2015 = 402 ppm
predictions of future climates say by 2050, earth's global temp will increase by?
1-3 C
3 important enviro functions of H2O
1. redistributes heat energy through latent heat energy exchange 2. condensation of it creates precip providing needed fresh water or planet/animal consumption 3. helps warm atmosphere through greenhouse effect
composition of atmosphere - gases. how many common ones, which ones important to biosphere
12 common ones in lower atmosphere - N2, O2, CH4 (methane), N2O (nitrous oxide), O3 (ozone) all incredibly important to health of biosphere
living atmosphere
2.5 billion years ago to present - creation of ozone layer in stratosphere (protects from UV rays - without this living organisms would not be able to survive) this accelerated terrestrial life - life began to influence chemical composition of atmosphere--produced lots of O2 through photosynthesis - buildup of O2 (less than 1% to 21%) occurred 850-500 million years ago due to photosynthesis by ocean-like plants like algae - 500 million years ago O2 levels levelled off at 21% - humans continue to modify these gases around 1700s and still do
secondary atmosphere
4.0-2.5 billion years ago - 3.8 billion years ago atmospheric temp was cool enough to allow condensation of water vapour... rain! created lakes, oceans, etc. - volume of water bodies levelled off at 3.5 billion years ago - sedimentary rocks formed here due to rain washing out lots of CO2 from air, which then chemically combined at ground with Ca and Mg - O began accumulating in atmosphere due to photodissociation (chemical breakdown of water by sunlight), released O2 and photosynthesis - emergence of living organisms 3.8 billion years ago = important in creation of O2 and O3
when did earth come into being, it formed as what 3 material
4.6 billion years ago -formed as gas, particles of interstellar dust, and ice lumped together to form large mass until about 200 million years passed
global radiation transfers--average annual global partitioning of incoming shortwave radiation
50% of shortwave is absorbed at earth's surface, 20% absorbed by clouds and other gases/particles, 30% is sent back to space through reflection (represents earth's albedo) = SO 70% OF TOTAL INCOMING SHORTWAVE IS ABSORBED BY EARTH'S SURFACE AND EARTH'S ATMOSPHERE
initially what was earth's temp, then what happened at 4.4 billion years ago, what did the cooling also initially release
8000 C! - then 4.4 billion years ago the surface cooled enough to solidify magma into solid outer crust - this cooling also initially released large quantities of gas from lithosphere, mainly He and He into early atmosphere
what percent of longwave emissions meant to go back to space are intercepted and absorbed by greenhouse gases then sent back to earth?
90%!!!!!
most important gas for greenhouse effect? what percent of recent change in intensity of greenhouse process does it account for?
CO2!!! accounts for 63% of recent change in intensity of greenhouse process
radiation balance - one-to-one relationship? however, what differs?
a one-to-one relationship exists between object's ability to absorb and emit radiation... so the absorption of solar radiation by earth should be balanced with emission of radiation back to space, HOWEVER, the quality or wavelength of this emission may differ... wavelength is controlled by temp and temp of earth is much lower than the suns.
the three atmospheric processes that modify sunlight passing through
absorption, reflection, scattering - earth's atmosphere is NOT transparent to incoming solar radiation so these 3 processes occur
environmental lapse rate
actual rates of tropospheric temp change varying with altitude, location, and time of year - 6.5 C per 1000 m - used to forecast future surface air temps and likelihood of thunderstorms - overnight cooling near ground produces enviro lapse rate where temp increases with height from surface before beginning to cool again (temp inversion)
N2 and soils
addition of N2 to soils and water bodies supplies nutrition for plants
thermometer
any instrument used to measure temperature
aerosols - what are they, produced by what 2 processes
atmosphere containing variety of liquid droplets and solid particles - produced by both natural (water droplets, ice crystals, wind-blown soil particles, volcanic dust, pollen, smoke/soot from wildfires, salts from sea spray) and human processes (dust from cars and ag processes, smoke/soot from burning of vegetation, emissions from combustion of FF)
why is it so hard to measure temp in thermosphere
because thermometers measure temp through movement of heat energy... and here, the thermometer would lose more heat energy from radioactive emission than what it would gain from making occasional contact with extremely hot gas molecules
total cloud reflection depends on what 2 factors
cloud thickness and relative abundance of water droplets/ice crystals - thicker clouds = more particles = more reflectivity - when water changes from liquid to solid there is significant increase in reflectivity
what controls the amount of heat energy added to atmosphere by greenhouse effect?
concentrations of the greenhouse gases!! these are all increasing since industrial revolution so that means more heat energy is added bc of greenhouse effect than ever before
N2 - how does it return to atmosphere
dentrification! chemical process where solid forms of N are converted into Nitrogen gases (N2, N2O) by bacterial action
direct solar radiation vs diffused solar radiation
direct solar rad: insolation reaching earth unmodified by any of atmospheric process (atmospheric transmission) diffused solar rad: insolation reaching earth after altered by processes of SCATTERING
atmospheric transmission, aka called what, what is it, varies how
direction radiation! passage of radiation through atmosphere WITHOUT being absorbed, reflected, or backscattered - varies spatially and temporally due to changes in clarity of atmosphere
daily mean temperature
diving sum of the max and min daily values by 2
without greenhouse effect, what would happen
earth would be -18 C and most of life would perish = too cold
recent discussion on global climate models - one component not simulated well in global climate models is effect of what? bottom line of what recent global climate models say about net warming vs net cooling with clouds?
effect of clouds is not simulated well into global climate models!! yet clouds are very important to our global climate - bottom line: unsure if presence of more atmospheric moisture will cause net warming or cooling of earth
meteorological normal
finding average of a measured meteorological element, like surface air temp, over a period of years (min 30 years data); useful for planning future activities that rely on specific temp regimes
how is albedo best measured, what technology was first attempt at this
global measurements of earth's albedo best measured with sensors on orbiting space satellites - e.g. NASA's Earth Radiation Budget Experiment (ERBE) was one of first attempts of making albedo measurements
greenhouse effect process
heating of earth --> causes ground to become longwave energy radiator --> emissions directed to space and 90% are absorbed and intercepted by greenhouse gases causing additional heat energy added to atmosphere --> greenhouse gas molecules begins addicting longwave energy in all directions, but mostly back to earth's surface --> net result is average global temp 33 C warmer than it would be without greenhouse effect
examples of high and low albedos
highest albedo is fresh snow -- super reflective - then high to low albedo examples: day old snow, dry sand dune, sea ice, wet sand dune, water with LOW sun angle, asphalt, black top road, water with HIGH sun angle - albedo gets higher as an object gets lighter in shade!
nitrous oxide - N2O. increasing at what rate, contributes to what, it is increasing because of what
increasing at a rate of 0.2-03% - another greenhouse gas - contributes to artificial fertilization of ecosystems (and extreme cases this fertilization can lead to death of forests, eutrophication of aquatics, and species dying off) - other reasons its increasing: land-use conversion, FF combustion, biomass burning, soil fertilization (50% increase due to this), and most of N2O added due to deforestation nd conversion of forest/savanna/grassland into agricultural fields
temperature inversion
inhibits upward movement of air currents and can cause creation of air pollutants near earth's surface
solar radiation reaches earth's outer atmosphere only altered in what? why
intensity! due to the fact that light travels away from sun's surface like an expanding sphere (inverse square law tells us that more distance travelled = intensity of radiation decreases to one-quarter of its original quantity)
ionosphere and aurora borealis and aurora australis
ionosphere has role in creating these steps: release of clouds of subatomic particles from solar flares --> some particles captures in magnetic field --> redirects particles, sending to magnetic poles --> at magnetic poles, electrons enter ionosphere where energy is transferred to N and O gas in upper atmosphere --> when enough energy is absorbed, we see visible colour bands of light (the aurora)
where is highest insolation received on earth
just outside equator over oceans*, not directly on equator because lots of clouds form there esp. cumulonimbus clouds, reduces insolation received by 60-80 Wm2
non-selective scattering
large atmospheric particulates interact with incoming solar radiation - esp. with water droplets with diameters 5-100 micrometers - equally influences all wavelengths of visible and near infrared spectrum -- produces a scatter that has a colour that ranges from blue to white - when white occurs = reduced visibility i.e. fog! the water droplets redirect the light in all directions producing white haze/poor visibility
for both jan and july, what surface of earth has lowest albedo? shfits seasonally how?
lowest surface albedo occurs over oceans in a zone that covers more than 100 degrees of latitude! between 8-13% albedo, with center of this zone shifting seasonally (in july = low albedo zone is tropic of cancer 23.5 N), in jan = tropic of capricorn 23.5 S)
instrument shelter
measures surface air temp in the SHADE and over grassed area - WMO recommends Stevenson Screen: houses max and min thermometers, white wooden box, elevated at 1.5 m i.e. 4.5 ft, ventilation for fresh supply of air, mounted on grassed area
counter-radiation
movement of longwave radiation back to earth's surface - if energy were not added back to the surface, longwave output from ground would only be 20 units! thus, the greenhouse effect, reemission of longwave radiation by greenhouse gases back to earth's surface, recirculates 74 units of energy
greenhouse effect
naturally occurring process aiding in heating earth's surface and atmosphere. resulting from gases such as H2O, CO2, CH4, and N2O able to change energy balance of planet by absorbing longwave radiation emitted from earth
atmospheric absorption - what wavelength band is especially susceptible to this
near-infrared band
if absorption exceeds radiation loss of emission
object heats up
if radiation loss of emission and absorption are the same
objects remains same temp
mie scattering
occurs with atmospheric particulates that are 1-10x larger than wavelength of solar radiation (at 0-5 km altitudes) - influences wavelengths of sun that are longer - dust, pollen, smoke, water droplets = main types of particles that cause this form of scattering - importance in creation of red skies at sunrise and sunset (atmosphere loaded with additional particles from dust storms, forest fires, exploding volcanoes = more sensational red sunrise/sunset)
ocean albedo and higher latitudes
ocean albedo increases at higher latitudes because of low sun angles and presence of sea ice
shortest time surface air temp is expressed is how long?
one day - midnight to midnight
in jan, most of southern semi in terms of net radiation?
positive net radiation in most of south semi in january because this is their summer and they have higher sun angles and longer days - so this is true for northern semi in july.
scattering's 3 processes
rayleigh scattering, mie scattering, non-selective scattering
aerosols - size ranges from what, small vs large aerosols length in atmosphere, average length of time in atmosphere
readily visible to specks of matter 0.2 micrometers - small particles float longer in atmosphere, large particles fall our of atmosphere in hours or minutes - average amount in atmosphere = few days to several weeks
global dimming
reduced emission of particles received in populated regions, counteracting some of increased warming predicted from human mediated enhancement of greenhouse effect LESS RADIATION REACHING EARTH
not all direct and diffused radiation available at earth is absorbed... some is redirected by what?
reflection! surface's albedo = surface's reflectivity - total earth's reflectivity is about 30% -- low albedo
methane - CH4. increasing how much, do to what
since 1750 CH4 has increased 150% primarily due to rice cultivation/rice paddy flooding (aerobic conditions); this process has doubled since 1950 -- other reasons CH4 is increasing: domestic grazing animals, herbaceous digestion, termites, landfills, oil and gas extraction, coal mining (least reason)
scattering
small particles and gas molecules diffuse part of incoming radiation in random directions - does not alter wavelength of rays, just alters how much rays reach earth... 20% of scattered shortwave radiation is redirected back to space
maximum minimum temperature system (MMTS)
special, smaller instrumentation taking temp readings continuously - white ventilated shelter, has internal electrical thermistor* (thermal resistor; measures temp based on electrical resistance of conductor) - computerized data storage device - can determine max, min, and mean temps daily!
subtle seasonal variations in long wave radiation from jan to july?
subtle seasonal variations - in jan, longwave emissions from middle to high latitudes are lower than same locations in southern hemi (because southern semi locations emit more long wave radiation because they are experiencing summer and high temps in jan)
atmospheric absorption - what is it, according to wein's law says what, and what type of molecules cause absorption
sunlight is absorbed by a particle found in the atmosphere, transferred into heat energy, and then converted into longwave radiation that is emitted back to surrounding enviro -- e.g. this is reason the thermosphere is so faaacking hot - according to Wein's law--bodies with temps at this level or lower would emit their radiation in long wave band and in all directions! (so lots of energy is lost to space) - absorption can occur due to presence of atmospheric gases, aerosols, clouds, precip particles
atmospheric reflection - what is it, most of reflection is off what
sunlight is directed by 180 degrees after it strikes an atmospheric particle, often causing 100% loss of insolation to space - most of reflection is off clouds when light is intercepted by particles of liquid and frozen water -- average reflectivity is 60%
most common measure of heat energy recorded regularly? how many weather stations
surface air temp -- recorded at 15,000 weather stations all over world, and the readings are transmitted electronically and used to construct weather maps and forecasts
annual mean temp
take all means of month temps and divide by 12 months
jan vs july when you combine surface AND atmospheric reflectivity which includes clouds? (planetary albedo)
this planetary albedo changes now because of clouds -- significant band son reflective clouds exist over equator and in mid-lats
annual global radiation cascades----global LONGWAVE radiation cascade
three different processes with radiation leaving earth - sensible heat: conduction, convection, advection--7 units energy - latent heat: 23 units energy--when water condenses to vapour and solidifies into solid - longwave radiation: 114 units*--mostly absorbed by greenhouse gases and converted into heat energy (atmosphere emits 152 units of longwave energy in total -- extra 50 units comes from absorption of shortwave by gases/aerosols, transfer of sensible heat, and transfer of latent heat
net radiation, what is it and equator, net radiation of entire earth should be what
total quantity of radiation of all wavelengths available to do work, composed of 4 parts: incoming shortwave - outgoing reflected shortwave = incoming longwave - outgoing longwave - net radiation of entire earth SHOULD be zero because the planet is in radiative balance (input = balance)... but there is a geographical imbalance - net radiation at night = lower net radiation on clear night than cloudy night
water and albedo
water tends to absorb more than 95% of insolation falling on it (low sun angle = MUCH more reflective than high sun angle though)
where is outgoing emissions of longwave the greatest?
where skies are clear and surface temps are high!
how does insolation received on earth change with increased latitude
with increased latitude, amount of insolation received decreases
