exam #3 Flashcards
Define UHI, why is it a problem? why is it largely a nighttime phenomenon?
UHI: urban heat island
urban areas can be up to 5 degrees warmer, dust dome of airbone pollution gets trapped.
the air warms during the day but due to UHI, there isn’t an escape of LW cooling at night
summary of causes of UHI
- increased absorption of sw radiation due to increased surface area and reflection
- increased lw radiation form sky due to air pollution
- decreased lw radiation loss due to canyon geometry and restricted sky view factor (dust dome and building don’t allow for view of sky)
- anthropogenic heat source due to building and traffic heat loss
- decreased evapotranspiration since construction materials increase impermeability and the water is filtered away -> less evaporation -> less heat exchange
- increased heat storage since the construction materials increase thermal admittance (glass, concrete, asphalt)
- decreased total turbulent heat transport due to canyon geometry -> reduction of wind speed means less displacement of heat
which 3 causes of UHI are highlighted?
- decreased lw radiation loss due to canyon geometry and restricted sky view factor (dust dome and building don’t allow for view of sky)
- decreased evapotranspiration since construction materials increase impermeability and the water is filtered away -> less evaporation -> less heat exchange
- increased heat storage since the construction materials increase thermal admittance (glass, concrete, asphalt)
which important factor limits radiative cooling at night in urban areas
restricted sky view
- much of the lw emitted is absorbed and re-emitted to the surface
define air pressure and wind. describe instruments used to measure each
air pressure: weight of the atmosphere described as force per unit area. key to understanding wind. use a barometer to measure atmospheric pressure: aneroid barometer or electronic sensors
wind: generally horizontal motion of air across earth’s surface. anemometer: measures win speed. wind vane: determines wind direction.
explain the four driving forces within the atmosphere
they determine the speed and direction of winds.
- gravitational force
- pressure gradient force: air driven from high barometric pressure to low
- coriolis effect: makes wind travelling in a straight path to appear to be deflected in relation to the earths rotating surface
- friction effect: friction between air and surface slows wind
explain several types of local and regional winds: surface winds, sea breeze, mountain valley winds
surface winds: coriolis force not perpendicular to pressure gradient force. wind crosses isobars at an angle.
sea breeze: diagram during the day, warm land and cool ocean -> low pressure on land to high pressure on ocean and creates loft sympathetic response. during the night, cool land and warmer ocean means H P on land and L on ocean, mirrored sympathetic loft response
mountain valley winds: diagram during the day, warm air rises up the slopes of the mountain = valley wind. L P on mountain and H P in valley. at night, cold air flows down mountain = mountain wind. H P on slope, L P on valley
warm, humid air is associated with low/high pressure and cold, dry air is associated with low/high pressure
warm, humid air: low pressure
cold, dry air: high pressure
which way does an easterly wind blow?
E to W
what’s an isobar? if they’re close together what does that mean?
lines of equal pressure on weather maps. closer together = greater the pressure gradient force and faster the air movement from a high-pressure area to low pressure
Why is pressure constant at surface but not at loft, how do you generate a wind at a loft/what comes of that? diagram
a) identical pressure at the beginning. expected at night
b) sun rises and heats different ground surfaces differently. air in A is warmed and it expands so the column rises and more air is above A so there is more pressure. a pressure gradient is created/
c) air moves across the gradient in the loft which creates a sympathetic response at the surface which causes pressure to rise in B and fall in A
which way to apparent forces deflect in each hemisphere. what is the coriolis force dependent on?
northern: right
souther: left
dependent on latitude. maximized at the poles due to rotational movement of the surface whereas it is zero at the equator due to earth’s rotation being translational
define geostrophic winds
balance between pressure gradient force and coriolis force
describe how thermal circulation systems occur
cool surface = high P
warm surface = low P
air flow high to low
air rises and an area of low pressure develops at the surface decreasing density. the loft mirrors what’s happening on the surface and high P occurs above.
air flow high to low in loft.
air sinks and an area of high pressure develops at the surface.
define climatology
scientific study of climate and climatic patterns and the consistent behaviour of weather
arrange the tools in paleoclimatology from most recent to oldest
ocean cores, sedimentary rocks, instrument records, tree rings, lake sediments, pollen, satellite data, documentary evidence, polar ice cores
satellite data, instrument records, documentary evidence, tree rings, polar ice cores, lake sediments, pollen, ocean cores, sedimentary rocks
why do we look at ice cores to understand the past?
we can look at the bubbles of atmosphere trapped within the ice cores to understand the concentrations of the atmosphere of that time.
define glacial and interglacial periods and how long they last
glacial periods: ice ages (100ka)
interglacial periods: ice sheets retreat (20-40ka)
when was the last glacial period? how long did it last?
pleistocene ~1800 years
list the order of the glacial and interglacial periods from latest to oldest
wisconsinan glacial
sangamonian interglacial
illinoian glacial
yarmouthian interglacial
kansan glacial
aftonian interglacial
nebraskan glacial
when was the last major warm interval? what was it called
piliocene: 3-4 million years
why do we have cycles in the eaeth/sun geometry and what does that mean for climate (12 pts)
what is the global temperature difference between glacial and interglacials?
5 degrees
when did the first major glaciation occur?
pleistocene
what is the current interglacial period and when did it begin?
holocene: 10-12000 years ago
sunspots vary in a __ year cycle
11
what is the maunder minimum? when was it from?
period when sunspot activity was very low and global temperatures were cooler (1645-1715)
whats the basis behind the normal form of climate variability that you can see
whats the geometry behind solar system physics and its effects on climate
the E received at the top of the atmosphere will vary if the motion of the Earth relative to the sun is not constant
what did milankovitch show about earth’s orbit?
three variations in the earth’s orbit that result in ~5% variation in the E received, especially at high altitudes the combined 3 effects explain the overall pattern of warming and cooling but not the speed of onset and end of glacial periods
outline the 3 cycles that are the variations in earth-sun geometry. what is their impact/how do they operate and how long is their cycle
- orbital eccentricity (stretch), 90,000 years, orbit changes from nearly circular to more elliptical, causes greater seasonality in one hemisphere and reduces it in another
- change in tilt of axis of rotation (roll), 41,000 years, orbit varies from 22 to 24.4 degrees, greater tilt means greater seasonality in both hemispheres
- procession of the equinoxes (wobble), 22,000 years, affects the timing of the aphelion and perihelion relative to the seasons, makes winters milder and summer warmers in the northern hemisphere and winters colder and summers warmer in the souther hemisphere
list potential internal changes within the earth’s system
formation of mountain barriers, volcanic eruptions, changes in ocean currents/salinities, massive calving of ice into the north atlantic, positive feedback
how was the original age of the earth established? what was the day?
added up years in the bible based on a known event. october 22, 4004 BC
why couldn’t people just add up all the rock layers to determine the age?
sedimentation rates varied substantially
where was the stuff left over from the creation of the solar system?
in the asteroid belt between mars and jupiter (separates jovial and terrestrial planets)
explain how we can use uranium to lead to calculate the age of the earth
atomic decay could calculate the rate of atomic decay
why can’t we use rocks on earth to date the age
none survived
why was the concentration of lead always off in pat’s tests
too much background lead present (ambient lead in the environment prohibited a clear measurement)
what instrument did pat use to measure the amounts of elements in the sample?
mass spectrometer (vaporizes and separates elements)
why did we use lead for roman plumbing?
cheap, slaves, easy to work with
why is lead toxic to humans?
lead mimics enzymes (zinc/iron) and when it gets into cells it prohibits the enzymes from doing their job
what was the additive used in leaded gasoline?
Tetraethyl lead, fat soluble -> will dissolve into an organism easily
who was robert keyhoe?
scientific expert for the lead industry…. Special interest groups will often hire their own people, to raise suspicion/doubt. Language used was that evidence didn’t support these things (wording)
how did pat know that lead levels in nature were typical but not natural
Because they were not seen in deep ocean water or glacial ice. Deep water takes a long time to cycle with surface water -> Long residence times = Samples are isolated from surface. Lead in surface vs deep water lead content was super different
how can you measure decay in a rock? how would you establish the time of earth?
dating uranium/lead, using meteorite samples
what are the four terrestrial planets?
mercury, venus, earth, mars
what are the four jovian planets?
jupiter, saturn, uranus, neptune
what are the 3 dwarf planets?
ceres, pluto, 2003 UB313
from the sun outwards, list the planets in order. include the asteroid belt
sun, mercury, venus, earth, mars, asteroid belt, jupiter, saturn, uranus, neptune
from the inside out, name the earth’s layer’s and their depths
solid inner core: 1220km
liquid outer core: 2250km
solid lower mantle: 2230km
partially molten upper mantle: 670km
crust: 16-40km
what are the main ideas of uniformitarianism and catastrophism
uniformitarianism: earth is old. processes take time to form the earth
catastrophism: earth is young. catastrophic events form earth.
what’s the oldest rock?
2008, acasta gneiss fround in NWT
how many years do each of the following intervals depict? eons, eras, periods, epochs, ages
eons: hundreds of millions - billions
eras: many million of years (distinctive fossil records)
periods: millions (distinctive rock unites)
epochs: few million
ages: thousands
why is earth a dynamic planet?
earth’s surface (crust) is in an ongoing state of change
explain endogenic vs exogenic processes/systems. what is powering them?
endogenic: internal system, flows of heat and material from below Earth’s crust powered by radioactive decay of unstable elements ex: mountain building, earthquakes, volcanoes
exogenic: external system, motion of air/water/ice powered by solar energy. ex: all processes of landmass denudation like chemical weathering and landslides
what is earth’s crust made out of?
crust: outermost rigid layer, varies in thickness depending on ocean (8-10km) and continent (~40km)
continental crust: lower density, granite
oceanic crust: higher density, basalt
what is earth’s interior made of?
mantle: mostly solid, ~2900km
inner core: solid iron
outer core: molten iron
what is the magnetic field and magnetosphere generated by?
fluid outer core
what’s the average period of geomagnetic reversals?
500,000 years
endogenic/exogenic?
building landforms
eroding landforms
endogenic: build
exogenic: erode
what are the 8 major elements in the rock cycle?
oxygen, silicone, aluminum, calcium, sodium, potassium, magnesium
what’s the difference between magma and lava?
magma is liquid rock below the earth’s surface while lava is on the earth’s surface
how are igneous, sedimentary and metamorphic rocks formed?
igneous: heated, melted, solidifies
sedimentary: sand/grain pushed together and compressed until it forms a rock
metamorphic: subject to heat and pressure, it forms a new chemical. heated, pressed but not melted
draw the rock cycle
for minerals and rocks, tell me: the study, chemical composition, examples, colour, shape and fossils
minerals: mineralogy, definite chemical composition, gold/silver/fluoride, same colour, has a shape, no fossils
rocks: petrology, no definite chemical composition, limestone/basalt/coal, not same colour, no shape, some fossils
PICTURES OF ROCKS
what’s the difference between intrusive and extrusive rocks?
both igneous rocks, intrusive are formed under the earth’s surface (granite) and extrusive are formed on the earth’s surface (basalt)
define the three main types of plate coundaries
convergent: coming together
divergent: going apart
transform: moving together
convergent oceanic plates and continental plates result in what?
convergent oceanic plates: islands
convergent continental plates: mountains
what are the 3 main stress types, which faults are the result? 2 strains?
stress:
1) tension: stretching
- normal fault
2) compression: shortening
- thrust fault
3) shear: twisting
- strike-slip fault
strain: response to stress
1) folding: bending
2) faulting: breaking
define focus and epicentre
focus: point of failure
epicentre: point on surface above focus
where are the 3 places that volcanoes are found?
subduction boundaries, sea-floor spreading centres, hot spots
define effusive vs explosive volcanic activity. where do they occur? what’s their chemistry and viscosity?
effusive: low-viscosity magma, < 50% Si, rich in Fe and Mg. gentle pour out of lava, small explosions. sea-floor spreading centres and hot spots.
explosive: high-viscosity magma, 50-75% Si, high in Al, dramatic explosions. subduction zone
what are the characteristics of shield volcanoes and the lava that comes out of them?
gentle slopes and horizontal dimension. basaltic lava: expansive flows but less violent. hot spots and spreading zones.
give two examples of a hot spot? which one is also a plate boundary?
iceland and hawaii. iceland
what are the characteristics of composite volcanoes and the lava that comes out of them?
symmetric, steep and high elevation. viscous or explosive lava. subduction zones.
what are the characteristics of cinder cones and the lava that comes out of them?
built around a single vent, lava flows are rare, steep
what is caldera?
collapsed volcanic cone
how you measure decay in a rock, how to establish the time in earth**
How did pat establish the age of the earth? Where was the source of lead coming from? How did we know what was natural vs typical?
originally, the age of the earth was established as october 22, 4004 BC because people compared a known event to the bible; however, the proper way the age of the earth was established was via atomic decay. uranium will spontaneously change into lead and the rate at which this happens can tell us the age of the earth.
by taking deep ocean samples that were isolated from the surface, we saw that there was no lead in the deep ocean meaning the amount of lead is not natural
granite is an intrusive/extrusive igneous rock. basalt is an intrusive/extrusive igneous rock
granite: intrusive
basalt: estrusive
