Biophysical Environment :(: Flashcards
define atmosphere
the blanket of gas that contains the air we breathe and also protects us from the blasts of heat and radiation from the sun
facts about the atmosphere
it is 480km thick air pressure decreases with altitude the layers of the atmosphere are (from top to bottom) exosphere thermosphere mesosphere stratosphere troposphere
troposphere
layer closest to the earth’s surface
7-20km thick (contains half the atmosphere)
nearly all the water vapour and dust are in this layer
stratosphere
above the troposphere
ozone is abundant - heats the atmosphere and absorbs the harmful radiation from the sun
air is dry and thin (1000x thinner than at sea level)
atmospheric processes
energy: sun provides the earth with its main source of energy (insolation)
sun exposure affects the climate (distance from the equator, aspect)
global patterns of climate
- variations in insolation (increased closer to the equator)
- rotation (on axis) and revolution (seasons)
- composition of the atmosphere (green houes gases, volcanic eruptions)
- distribution of the continents and oceans (warm and cold ocean currents, proximity to ocean)
- topography (eg mountain ranges, orographic rainfall)
comparing climates (sydney and prague)
Sydney:
high level of consistent precipitation
temperature is moderate / mild, lows of 12, highs of 22
coordinates: 33.9oS, 151.2oE (closer to equator)
Prague:
less rain, highs of 81ml, lows of 20ml
temperature: wide diurnal range (-1o to 18o)
coordinates: 80oN, 14oE
Weather
determined by air pressure, moisture and movement of air masses
what do synoptic charts measure
air pressure, rainfall, wind, temperature
Air
measured using a barometer (hPa)
isobars join places of equal pressure
the closer the isobars, the stronger the wind
Low Pressure System
area of increasing air, measures below 1013hPa
wind moves clockwise in the Southern Hemisphere
weather: unstable, chance of rain, cloudy
High Pressure system:
area of sinking air (above 1013)
direction = anti clockwise
weather: fine :)
Tropical cyclone
area of rapidly rising air (i.e. intense low pressure system), causing torrential rain, strong winds)
given names
need warm waters to form and generally disapate when hitting land
Cold front
air mass that separates cold and warm air, cold air behind
fall in temp, brings rain and storms
shows the direction in which its moving
warm front
air mass w warm air behind it (less common in Aus)
increase in temperature, light showers
Troughs - - - - and ridges
Regions of relatively low pressure that precede a cold front
associated with wet weather
winds in front of troughs
monsoon troughs
– - – - occur in NA through summer
Rainfall
/ / / /
/ / / rainfall in the last 24 hrs
oO
calm, no winds
Wind barb
indicates wind direction and speed (easterly means from the east)
. where it has been recorded
___ direction from
/ speed km/hr
aspect induced climates
face equator = more direct sunlights
(SH = northerly, NH = southerly)
easterly aspect = sunlight in the morning when the temperature is decreased
agricultural lands are found in areas of direct sunlight, ski slopes in Aus face east or south
Hydrosphere
total amount of water on the planet, including water on the surface, underground and in the air in the form of liquid, vapour or ice
Liquid, solid, gas
liquid: oceans, rivers, creeks + groundwater
vapor: clouds and fog
solid: icebergs, icecaps, glaciers
Water cycle
condensation, evaporation, transpiration, precipitation, runoff, infiltration, percolation
condensation
when water vapour in the air cools and turns back into a liquid
evaporation
when sun shines on water and heats it, turning it to vapour
transpiration
when the sun warms the biosphere and it releases water vapour into the air
precipitation
water falls from the sky as rain, snow or hail
run off
when water flows over the ground into creeks, rivers and oceans
percolation
when water seeps deeper into tiny spaces in soil and rock
water currents
warm water = anti cw from equator
hydrosphere shaping lithosphere
rivers and streams, collecting and carrying particles to deposit them elsewhere
vegetation binds the soil together
hydraulic action, abrasion, corrosion, land form evolution
hydraulic action
flowing water (dragging), excavating quantities of poorly consolidated alluvial materials
abrasion
rock particles carried by water strike channel walls
corrosion
chemical solution of material of rocks being exposed to the stream by solvents in the water
land form evolution
long term
steep gradients, river erodes downwards creating valleys
low hills, rivers begin to broaden, meanders develop
flats - lateral erosion, valleys widen
Biosphere
extends from a few kms into the atmosphere to hte deep vents of the ocean - composed of all living organisms and what gives them nutrients
factors affecting vegetation patterns
climate (precipitation, temperature, light, wind)
topographic (altitude, slope, aspect)
edaphic (soil quality)
biotic: plant competition, human activity
formation of land marks
erosion follows planes of weakness called joints, occuring in vertical sets
with progressive erosion, blocks of sandstone fall into the valleys, breaking off at joints
more erosion resistent rock such as narrabeen sandstone is left standing as the friable shales erode away
shaping of the landforms
water, wind, gravity
weathering causes undercutting, therefore there are sandstone overhangs which are further disjointed due to vertical fractures by water and roots - they fall cos of gravity
erosion widens the space between joints, leaving turrets
rainforests
moisture + steep terrain ensure protection
reliably moist, high levels of soil nutrients and minimal exposure to fire
closed canopy of soft horizontally held leaves and shade tolerant understory (ferns, vines)
coachwood, sassafras, cedar wattle, lilly pilly, mosses,
2m canopy, cool and shaded, southerly aspect, high biodiversity
heath land
shrubby, treeless, sparse shallow, nutrient poor, sandy soils exposed (usually ridge tops) high plateau 3ha warm temp, low humidity dwarf sheoak, hairpin banksia
comparing vegetation communities
temperature, humidity, aspect, topography, soil, vegetation type and diversity
Blue Moutnains Dam
- 3 small catchment areas feeding 6 dams (provides water for 41000 people)
- special areas :protect water supply by acting as a buffer zone, managed by WaterNSW and Wildlife Service –> public access is restricted to ensure quality of water, protect bushland, flora and fauna, evidence of aboriginal occupation
what do they want to do with the bm dam
- $670m plan to raise the dam wall by 4m to prevent flooding in outer-western sydney, however raising the wall would flood 4700ha and threaten endangered species, + 50 Aboriginal sites
