dynamic planet

what are the 5 spheres

- atmosphere

- cryosphere

- hydrosphere

- biosphere

- geosphere

what drives the rock cycle

the earths internal heat

what drives the hydrological cycle

the suns energy

define geochemical cycle

the cycle of mass/elements between the earths spheres

how do geochemical cycles work?

- the earth is tilted, spins and not materially hetrogenous

- this leads to some bits warming faster than others- this causes pressure and temperature gradients

- matericals and energy move thru these gradients

whatre the 2 diff models of the earth

1. chemical

2. mechanical

what is the chemical model of the earth

- based on changes in composition

- so crust, mantle, core

what is the mechanical model of the earth

- based on changes in RHEOLOGICAL behaviour (the study of how materias flow)

so, lithosphere, asthenosphere, inner core, outer core

what is the ultimate source of energy for atmospheric circulation

the sun

what is radiative equillibrium and how does it work

- the equillibrium between the total shortwave solar radiation entering to the total long wave infared radiation emitted by the earth

- this keeps earth temp stable

what would happen if we had no atmosphere

earths surface temp would be -18 degrees

what do GHGs do

- absorb outgoing infra red radiation

- re emit it in all directions

- some is sent back to earth

- this traps heat and causes warming

define albedo

the fraction of sunlight reflected by a surface

what 3 things does earths climate depend on

1. incoming solar radiation

2. albedo

3. GHGs

what would atmospheric circulation look like if the earth didnt rotate or tilt

1 circulation cell per hemisphere

- would be much simpler

coriolis effect

- due to the earths rotation that occurs whilst air is moving, as air moves from equator to poles, rotation speed also changes causing air to appear to turn right in the northern hemisphere, and left in the southern

- the coriolis effect results in getting 3 cells per hemisphere rather than one

what are the 3 cells per hemisphere from equatior to pole

1. hadley cell

- warm air rises at equator and sinks at 30 degs

2. ferrell

- the middle cell

- driven by the other two cells

3. polar

- cold air sinks at poles and moves twrds 60 degs

the inter tropical convergence zone

- the ITCZ

- located near the equator, is a low-pressure belt where trade winds meet, causing rising warm air, heavy rainfall, and frequent thunderstorms

polar front

- the boundary between cold polar air and warmer mid latitude air

- so we have 2 on earth duh x

jet streams

- found just above polar fronts

- very fast winds!

- winds move west to east

- theyre stronger in the winter

- they follow temperature boundarys (boundarys between hot and cold air) meaning they can move north and south depending on where these boundarys are

isobars

- lines connecting points of equal atmospheric pressure, which can indicate the distrubution of atmospheric pressure across an area

- are found on weather maps

- the closer the isobars, the greater the pressure gradient

what do isobars look like on a weather map for low pressure versus high pressure systems

- in LOW PRESSURE SYSTEMS isobars form closed circles with pressure DECREASING towards the centre

- in HIGH PRESSURE SYSTEMS isobars form closed circles with pressure INCREASING towards the centre

what does the distance between isobars mean for winds

- indicates a great pressure gradient, so STRONG WINDS

this is bcs wind moves from high to low pressure, so the greater the gradient the stronger the wind

whatre wind barbs

the point in the direction that the wind is coming from

the feathers on them show the speed of the wind

does wind flow DIRECTLY from high to low pressure

NO

- ends up flowing parrallel to isobars

verticle structure of the atmosphere

1. troposphere - 8-15km

2.stratosphere - 15-50km

3. mesophere - 50-85km

4. thermosphere - 85- 500+km

5. exosphere - outer layer

whats the tropopause

the boundary between troposohere and stratosphere

difference in temperature in the atmosphere

Temperature decreases with altitude in the troposphere primarily because the atmosphere is heated from the ground up, leading to cooler air at higher elevations.

BUT

from the stratosphere up, temp increases due to ozone absorbtion of UV

whats a saturation vapour pressure curve

- shows the max water vapour air can hold at a given temp

- warmer air can hold more moisture

different levels of saturation on a saturation pressure curve

1. LEFT OF CURVE = air is super saturated ( holds more water vapour than the max amount for that temp = very rare)

2. ON CURVE = saturated = at equillibrium

3. RIGHT OF CURVE = unsaturated

whatre the two types of ways to measure moisture

- absolute measures and relative measures

whatre the two absolute measures of humidity

1. vapour pressure = partial pressure of water vapour

2. dew point = temp air must cool to to become saturated

whats the relative measure for humidity and whys it a bit crap

RELATIVE HUMIDITY = actual vapour pressure/ saturation vapour pressure x 100

BUT its temp dependant, warm air can hold more water vapour, so the RH levels will differ even if moisture levels dont

the two ways to reach saturation

- add moisture

- cool the air

dry adiabatic lapse rate (DALR)

- when UNSATURATED air rises, it expands and cools at 10 degrees per km

- (bcs pressure decreases with height)

moist adiabatic lapse rate

- when the dew point of rising air is reached, and air becomes saturated, it starts cooling at 5-8 degrees per km

- this is cuz condensation begins and latent heat is released which offsets cooling

latent heat

the energy released when water vapour condenses

what doe all igenous rocks do

crystallize from magma

what are the three things magma is made of

1. liquid (usually silicate liquid)

2. crystals (minerals that havent melted)

the three places magma comes from

1. continental crust

2. oceanic crust

3. upper mantle

what is the magma like from the continental crust

- andesitic 'intermediate' magma

- higher SiO2 content

- high K2o and Na2O

- forms quartz, feldspars, fe and mg minerals

what is the magma like from the oceanic crust

- basaltic 'basic' magma

- lower SiO2 content

- high FeO, MgO, CaO

- forms olivine, pyroxenes and plagioclase

what is the magma like from the upper mantle

- peridotite 'ultra basic' magma

- lowest SiO2 content

- high FeO MgO

- forms Olivine and pyoxenes

where does the most melting on earth occur and what type of magma does this give rise too

- most melting occurs of the UPPER MANTLE and lower CONTINENTAL CRUST

- gives rise to 2 main types of magma

- ULTRABASIC and INTERMEDIATE

why dosent melting of rocks happen under normal conditions

the geotherm dosent intersect the solidus line

what is the solidus

the melting point of the rock, this increases with pressure

what is the geotherm

- the geo thermal gradient

- the rate at which temperature increases as we go down thru the earth

what are the three special conditions that allow rocks to melt

1. CHANGING THE GEOTHERM

- mantle plumes = upwelling heat = abnormally high temps

- cause hotspots and volcanic islands

2. DECOMPRESSION

- occurs at mid ocean ridges

- oceanic crust thins as its extended

- this decreases the pressure of the rocks, lowering their melting point

3.ADDITIONAL WATER

- when oceanic plate is subducted, water hydrates the rocks, lowering their melting point

what 2 things determine mantle composition

1. composition of the source

2. degree of partial melting

how does compositon of the source affect mantle composition

- if its from...

a) the mantle= ultrabasic = olivine, pyroxene, garnet

b) continental crust= intermediate= feldspar, micas, pyroxenes, quartz, amphiboles

how does the degree of partial melting affect mantle composition

- total melting is RARE as magma usual contains a variety of minerals w diff melting points

- so MAGMATIC DIFFERENTIATION DURING PARTIAL MELTING occurs, changing the comp of the magma

what is MAGMATIC DIFFERENTATION DURING PARTIAL MELTING

- minerals with a lower melting point melt first, leaving behind a residue of the higher melting point minerals

- THE MELT PRODUCED IS ALWAYS MORE ACIDIC/ FELSIC THASN THE PARENT ROCK

*** i dont acc know why, cuz surely more acidic= higher silica content= higher melting point... but hey ho!

what are the two reasons that magmas rise

1. theyre less dense

2. they can flow

( basic ---> intermediate ---> felsic)

in the brackets, the viscosity increases

whatre intrusive igneous rocks

rocks that crystallize beneath the earths surface

whatre the three types of rocks that arise from crystallization in diff places

1. PLUTONIC = deep crystallization = course grained

2. HYPABYSSAL = shallow crystallization

3. VOLCANIC = surface crystallisation = fine grained

whats a dyke

a vertical igenous intrusion

whats a sill

a horizontal igneous intrusion

whats a batholith

a large body of cooled magma

why do intrusive melts cool and crystallize slowly

1. rock is a shite conducter, so magma loses heat to the rock very slowly

2. the magma heats the host rock a little as well, slowing cooling further

3. and latemnt heat of crystallization also slows cooling

whats the coutnry rock

- the host rock

why do igneous rock sometimes have layers/ a porphorytic texture

- bcs of the complex mixture of minerals, when magma cools, higher M.P minerals crystallize first and sink , followed by the ones with lower melting points, creating layers

what is magma mixing

the mixing of 2 different types of magma to give a new homogenous one

what is stoping

the partial melting of the host rock can cause blocks of it to be incoorperated into the melt changing its composition

define a volcano

a rupture in a planets surface that molten rock/ gas/ ash escape from an underlying magma chamber

what two things does eruptive style depend on

1. viscosity

2. environment

how does viscosity effect eruptive style

- viscosity decreases with increasing temp

- felsic/ acidic magma = more viscous, as more SiO2

- higher dissolved water content = lower viscosity

- as magma ascends, pressure and temp and water solubility decreases, so the cyrstal content of the magmna increases, increasing viscosity

-

( at high press, water is dissolved but decreasin gpressure allows bubbles to form = fragmentation)

the two diff types of volcanic environments

submarine and subarial

charecteristics of submarine volcanoes

- largely mantle melt, so basic lava

- but when subducted below a continental plate = intermediate magma

- magma = high water content = low viscocity

- high pressure keeps gasses dissolved forming a type of laval called PILLOW LAVA

whats pillow lava

as the lava erupts a glassy rind forms when it comes in contact with water

- the volcanoe grows as pillow lava tumbles down and builds up the sides

- as it grows, feeding dykes intrude

- as u get higher, water pressure decreases so bubbles can form, eruptions become more explosive

- pillow lavas stop being produced, instead, HYALOCLASTITES

charecteristics of subareal eruptions

- high variability of melt composition

- material either erupts as lava flow or pyroclastics

lava flows

- occur when magma is basic - intermediate

- Pahoehoe = hot runny smooth and fast lava

- 'A'a = cool thick rough and slow lava

- thick slow cooling lava can develop columnary jointing

what is columnary jointing

made of two parts

- colonndae = regular columns with 3- 8 near planar sides

- entablature = thinner less regular columns with curving sides

pyroclastics

occur in two forms

- PYROCLASTIC FALL DEPOSITS

and PYROCLASTIC FLOW AND SURGE DEPOSITS

pyroclastic fall deposits

- the most basic type of pyroclaztcs

- debris falls from the eruption column

pyroclastic flow and surge deposits

material and gas form a mixture, mixture is denser than the surrounding air so it collapses under gravity and tumbles down the volcanoe hugging the side

- the coarser material gets deposited first

- super dangerous

different categories of volcanic material

- ash = < 2 mm

- lapilli = 2-64 mm

- bombs/ blocks = >64mm

overall type of volcano for basic - intermediate magma

- low explosivity

- lava> pyroclastics

- regular eruptions

overall type of volcano for intermediate - acidic magma

- high explosivity

- pyroclastics > lava

- irregular eruptions

4 eruption types

1. hawaiin = effusive

2. strombolian = fluid lava, very tall eruptions

3. vulcanian = short violent, viscous, small amts of ash and gas

4. plinian = most explosive, pyroclastic flows and ash clouds

four volcanoe types

1. sheild = largest volcanoes on earth, basic magma

2. strato volacnoes = acidic - intermediate magma, moderate - high explosivity, viscosity and pyroclastics, have some lava too, steep sided

3. lava domes = basic - intermediate lava, low explosivity and pyroclastics, moderate to high viscosity, smaller

4. cinder cones = low - moderate viscosity, lots of pyroclastics, basic - acidic magma, small again.

what is an extratropical cyclone

a large scale low pressure system that forms outside of the tropics, along the polar front

the norweigen cyclone model

- by vilhelm bjerknes, a meterologist

- describes the life cycle of cyclones

how do cyclones move in the N hemisphere vs the south

- winds spiral inwards in both cases

- turns counterclockwise around low pressure in the norht hemisphere

- clockwise in the south hemi

how does a cyclone form PART 1

1. rosby waves cause and ungulation in the jet stream

2. this causes a pertubation on the front

3. wind circles around the pertubation causing the front to slope and deform over time

what is the warm front

- when warm air moves poleward, its the boundary where warm air is advancing and replacing cooler air

what is the cold front

- when cold air moves equatorward, its the boundary where cold air is advancing into warmer air

the development of a cyclone PART 2

1. a warm conveyer belt approaches the cyclone from the south, and hits the sloped front, rising up into the njet stream where it splits

2. part of it turnns east and the rest turns west and wraps around the cyclone

3. cold converyer belt approaches from the north or east, staying close to the earths surface underneath the warm conveyer belt

4. a dry air stream from the upper atmosphere creates the comma shape of the cyclone

5. the warm section rises aloft the cold air and shrinks

6. this, and the cycling of air means the cold air expands at the surface

end of cyclone lifecycle PART 3

eventually the fronts wrap up and form an occluded front

this is a merger between cold and warm fronts

whats a stationary front

-when cold air moves north and warm air moves south, so they stay in their boundarys, with winds flowing parallel

- there is a strong temp gradient, givign potential energy for a cyclone to occur

what three things can cause a cyclone to intensify

1. upper level divergence = when air is removed at higher altitudes, leading to rising air and lower pressure

2. strong temp contrasts

3. rapid drop in surface pressure

whats barocliic instability

when surfaces of constant pressure and density (isobars and isopyncals) are not aligned

this can cause / stengthen ETC's

why does the jet stream exist

bcs the equator is warm and poles are cold, causing strong horizontal temp grads

- strong temp grad = stronger pressure grad = stronger horizontal winds

THEN,

stronger wind = stronger coriolis force = stronger deflection

eventually deflection perfectly balances the PGF = GEOSTROPHIC BALANCE = a jet stream

how do jet streams control weather

- steers cyclones = they follow the jet stream like a track

- creates cyclones = storm intensifys under jetstreaks (regions of esp strong winds)and upper divergence

- influnces weather patterns thru zonal flow

what is meant by meridonal flow

- wavy jetstream

- extreme temps

whatre rosby waves

- large scale meanders in the jet stream

- can cause meridonal flow

- occur due to diffeerences in the strength of the coriolis force

how does satellite imagry work

measures radiation from clouds and earth

the 3 types of satellite imagry

1. visible satellite = uses reflected sunlight, only works in day time, shows cloud structure

2. IR = measures cloud top temps, cold cloud tops = high altitude clouds

3. h20 vap = shows moisture in upperatmosphere, reveals jet stream patterns

radar imagry

sends pulses, detecting reflected signals from rain, hail, snow

- shows precip intensity and storm movement

what froms on the boundary between ferrel and polar cell

ETCs.

jet stream forms above this boundary

conditions for lightning

- mixed ph\se cloud (liquid and solid water)

- graupel and ice crystals

- collisions of graupel and ice cause e- transfer causing a charge seperation creating an electric feild