Natural Systems
Question Answer
What are the five key parts of a system? Inputs, outputs, stores, flows and boundaries
What is an input? Matter or energy that is added to the system
What is the input in a drainage basin? Rain
What is an output? Matter or energy that leaves the system
What is an output in a drainage basin? Where the river meets the sea
What is a store? Where matter or energy builds up
What is a store in a drainage basin? The soil and vegetation
What is a flow? When matter or energy moves from one store to another
What is a flow in a drainage basin? Evaporation, river channels
What is a boundary? The limits of the system
What is a boundary in a drainage basin? The watershed
In an open system ... ... energy and matter can enter and leave the system
What is an example of an open system? Drainage basins
In a closed system ... ... only energy can enter and leave the system
What is an example of an closed system? The carbon cycle
If inputs and outputs are balanced, the system is ... ... in equilibrium
When a system is in dynamic equilibrium ... ... average inputs and outputs remain the same
What is positive feedback? Where mechanisms amplify the changes in inputs and outputs
In positive feedback, the system moves ... ... further away from its previous state and dynamic equilibrium
What is the albedo affect? The ability of a surface to reflect sunlight
Give a positive feedback loop in the water cycle relating to the albedo effect. Temperature rises -> ice melts -> less ice cover means less albedo effect -> earth absorbs more solar energy ->
Temperature rises
What is a negative feedback system? Where mechanisms counteract the impacts of earlier changes in the inputs or outputs
In negative feedback, the system moves ... ... closer to its previous state and dynamic equilibrium
Give a negative feedback loop in the carbon cycle relating to plant growth. CO2 is emitted -> CO2 in atmosphere increases -> plants grow more -> plants remove and store CO2 -> CO2
decreases
Why is the Earth a closed system? Only energy is input by the sun and output into space
What is the cryosphere? All parts of the earth where it is cold enough for water to freeze
What is the lithosphere? The outermost part of the Earth, including the crust and upper parts of the mantle
What is the biosphere? Where living things are found, including plants, animals, fungi, insects and bacteria
What is the hydrosphere? All the water on Earth in liquid, solid and gas form, saline or fresh
What is the atmosphere? The layer of gas between the Earth's surface and space, held in place by gravity.
Subsystems are interlinked by ... ... cycles
What is the cascading system? Where the output of one subsystem is the input of the next
The Water Cycle
Question Answer
How much water does the hydrosphere contain? 1.4x10^20 l
What percentage of the hydrosphere is saline oceanic water? 97%
What percentage of the hydrosphere is freshwater? 3%
,What percentage of the world's freshwater is frozen in the cryosphere? 69%
What percentage of the world's freshwater is groundwater, stored in the lithosphere? 30%
What percentage of the world's freshwater is liquid on the Earth's surface? 0.3%
What percentage of the world's freshwater is stored as water vapour in the atmosphere? 0.04%
For humans to use water, it must be ... ... physically and economically accessible
Why is groundwater not cost effective to extract? It is hard to access
When water boils or melts, it ... ... gains energy
When water condenses or freezes, it ... ... loses energy
What is water as a closed system known as? The global hydrological cycle
Which four stores does water pass through? The hydrosphere, lithosphere, cryosphere and atmosphere
How much time does water spend in soil water? 1-2 months
How much time does water spend in rivers? 2-6 months
How much time does water spend in snow? 2-6 months
How much time does water spend in glaciers? 20-100 years
How much time does water spend in lakes? 50-100 years
How much time does water spend in shallow ground aquifers? 100-200 years
How much time does water spend in deep ground aquifers? 10,000 years
What is evaporation? Liquid water changing into water vapour by gaining energy from solar radiation
Evaporation causes the atmospheric store of water to ... ... increase
What are the conditions for evaporation to be high? Lots of solar radiation, large supply of water and warm dry air
What are the conditions for evaporation to be low? Little solar radiation, little available liquid water and cool saturated air
What is condensation? Water vapour changing into liquid by losing energy to its surroundings
When does condensation occur? When water vapour cools to its dew point
What is the dew point? The temperature at which relative humidity becomes 100% so the air can't hold any more water vapour, and below
this temperature, it condenses to a liquid
Why might condensation occur at night? A lack of solar radiation so heat is lost to space
What are condensation nuclei? Tiny particles that water molecules condense on
Give an example where water droplets flow into other subsystems. Water vapour condenses, forming dew on leaves and decreasing the water stored in the atmosphere
What is the condition for condensation to be high? Lots of water vapour and a large temperature drop
What is the condition for condensation to be low? Little water vapour and a small temperature drop
How do clouds form? Warm air cools down, causing water vapour to condense into water droplets which gather as clouds
When water droplets in clouds get big enough, they ... ... fall as precipitation
For what 3 reasons can warm air cool down? Density, topography and convection
How does frontal precipitation occur? When the less dense warm air rises above cool air and it cools down to fall as precipitation
How does orographic precipitation occur? When warm air meets mountains, is forced upwards and cools down to fall as precipitation
How does convective precipitation occur? When the sun heats up the ground, moisture evaporates and rises as a column of warm air, then cools to fall as
precipitation
What is accumulation? The input of snow and ice into a glacial system
What is ablation? The output of water from a glacial system
In a glacial system, during a period of global cold, the inputs are ... ... greater than the outputs
In a glacial system, during a period of global cold, water ... ... increases in the cryosphere and decreases elsewhere
, In a glacial system, during a period of warmer global temperatures, the outputs are ... ... greater than the inputs
In a glacial system, during a period of warmer global temperatures, water ... ... decreases in the cryosphere and increases elsewhere
When did the Earth's last glacial period peak? 21,000 years ago
Where does the Earth still have large stores of ice on land? Antarctica and Greenland
Where does the Earth still have large volumes of sea ice? Arctic and Antarctic waters
Changes in global temperatures can occur ... ... over thousands of years and annually
Sea ice is formed when ... ... ocean water is cooled to below freezing
How much sea ice did the Arctic have in 1980? 7 million km^3
How much sea ice did the Arctic have in 1910? 4 million km^3
Give an example of sea ice. The Frozen Arctic Ocean
Sea ice might melt in the summer and as a result of global warming, but ... ... it does not raise sea levels
Give an example of an ice sheet. Antarctic and Greenland ice sheets
What are ice sheets? Masses of glacial land ice extending more than 50,000 km^2
How long does it take for ice sheets to form? Thousands of years
How do ice sheets form? Snow from the winter does not completely melt in the summer and the snow builds up, compresses and becomes ice
which is constantly moving
How might ice sheets lose ice? Glacial melt at the base of the ice sheet in summer and warmer times
How do ice sheets remain stable? They tend to accumulate the same mass of snow as it loses to sea
What are ice caps? Thick layers of ice on land smaller than 50,000 km^2
Give an example of an ice cap. The Furtwangler ice cap, Kilimanjaro
When do ice caps melt and shrink? In the summer and warmer climatic times such as interglacials
What are alpine glaciers? Thick masses of ice in deep valleys
Give an example of an alpine glacier. Himalayan glaciers
During summer and interglacial periods, glaciers melt at their ... ... snouts and retreat
Melting glaciers can ... ... flood the rivers that they feed
What is permafrost? Ground that remains below 0ºC for more than 2 years
Give an example of permafrost. The soil and rock of Antarctica
During an interglacial, ice sheets and glaciers ... ... shrink and retreat
What can shrinking ice sheets lead to? Reduced albedo so the sun's radiation is absorbed by the sea and temperatures rise
What can temperature rise lead to? More storms and coastal erosion
During an interglacial, the reduction in albedo and so increase in temperature is an example of ... ... positive feedback
During an interglacial, how can CO2 be released? Melting ice and thawing permafrost
During an interglacial, how could the economy and politics be affected? Melting ice can open trade routes and access to fossil fuels
Easier fossil fuel access could lead to ... ... international conflict
During interglacials, surface water storage could ... ... increase as ice melts, meaning more freshwater available to people
During interglacials, what could certain animals and people lose? Habitats and indigenous cultures
Give an example of an animal that could lose its habitat in an interglacial. Polar bear
Give an example of people who could lose their indigenous cultures in an interglacial. Nenets in the Russian Tundra
During an interglacial, how could isostatic uplift occur? Shrinking ice sheets and glaciers place less weight on the land causing it to rise and sea levels to fall relatively
During an interglacial, melting ice could alter ... ... ocean currents, impacting the climate and marine life
