Water cycle Flashcards
What are the two types of system?
Open systems and closed systems.
Give an example of an open system:
A drainage basin- energy from the Sun enters and leaves the system. Water is an input as precipitation, and output as river discharge into the sea.
What cannot enter or leave a closed system?
Matter- it can only cycle between stores.
What can enter or leave a closed system?
Energy- it can be an input or output.
Give an example of a closed system:
The carbon cycle- energy is an input and output, but the amount of carbon on Earth stays the same because there are no inputs or outputs of matter.
What are isolated systems?
Where are these systems not found?
Where neither matter nor energy can enter or leave, and the system has no interactions beyond its boundaries.
These aren’t found in nature.
Natural systems often….
…. have multiple inputs, outputs, stores etc.
What happens when a system is at dynamic equilibrium?
Inputs and outputs are balanced, so flows and processes continue to happen, but in the same way at all times, so there is no overall change to the system.
Why is a system considered to be at dynamic equilibrium and not just equilibrium?
Because, in reality, there are lots of small variations in the inputs and outputs of a system.
These small variations mean that the system is balanced on average and so is said to be in dynamic equilibrium.
Large, long-term changes to the balance of inputs and outputs can cause…
… a system to change and establish a new dynamic equilibrium.
Why might a system change and establish a new dynamic equilibrium?
Due to long-term changes to the balance of inputs and outputs.
In a system, a change can trigger…?
Positive or negative feedback.
What is positive feedback and what does this mean?
Positive feedback mechanisms amplify the change in the inputs or outputs.
This means the system responds by increasing the effects of change, moving the system even further from the previous state.
Give an example of positive feedback:
Temperature rise
Ice covering cold parts of Earth melts due to higher temp
Less ice cover means less of the sun’z energy is reflected
Less of the sun’s energy being reflected means more more is absorbed by the earth
What is negative feedback and what does it mean?
Negative feedback mechanisms counteract the change in the inputs or outputs.
This means that the system responds by decreasing the effects of the change, keeping the system closer to its previous state.
Give an example of negative feedback:
Large amount of CO2 emitted
CO2 in atmosphere increases
Extra CO2 causes plants to increase growth
Plants remove and store more CO2 from atmosphere
Amount of CO2 in atmosphere reduces
What are the major subsystems of the water system?
Atmosphere Lithosphere Hydrosphere Biosphere Cryosphere
What is the cryosphere?
Subsystem of the Earth that includes all the parts where its cold enough for water to freeze, eg. glacial landscapes.
What is the lithosphere?
The outermost part of the Earth.
It includes the crust and the upper parts of the mantle
What is the biosphere?
The part of the Earth’s systems where living things are found.
It includes all the living parts of the Earth, eg plants, animals, birds, fungi, insects, bacteria etc.
What is the hydrosphere?
All the water on earth.
It may be in liquid form, solid form or gas form.
It can also be salty or fresh.
What is the atmosphere?
The atmosphere is the layer of gas between the Earth’s surface and space, held in place by gravity
Where is most fresh water found on Earth?
In the cryosphere, in ice caps, glaciers and permafrost.
Why does the distribution of freshwater storage on Earth create issues for humans?
Most of the freshwater on Earth is stored in the cryosphere.
This is an issue as it means most fresh water is largely inaccessible.
What percentage of fresh water is found in ice caps, glaciers and permafrost?
69%
What percentage of fresh water is found in groundwater?
30%
What percentage of fresh water is found in lakes?
0.25%
What percentage of fresh water is found in soil moisture?
0.05%
What percentage of fresh water is found in the atmosphere?
0.04%
What percentage of fresh water is found in swamps, marshes and wetlands?
0.03%
What percentage of fresh water is found in rivers?
0.006%
What is meant by potable water?
Water that is safe to drink.
What percentage of water is potable?
0.07%
What sort of system can the Earth be considered as?
A closed system- energy is an input from the sun and output to space, but matter is nto an input or output to space.
A cascading system- matter and energy moves between the subsystems (the output of one cycle is the input of the next).
Changes that occur in one subsystem…
… can affect what happens in the others.
How much of the Earth’s water is freshwater?
Less than 3%.
Most of it is saline water.
In order for humans to use it, what must water be?
Physically and economically accessible.
For water to melt or boil….
…. it must gain energy.
Eg. from the Sun.
For water to condense or freeze…
… it has to lose energy.
Eg. to the surroundings.
What is the global hydrological cycle?
Where water is continuously cycled between different stores.
When water is continuously cycled between stores it is known as?
The global hydrological cycle.
What type of cycle is the global hydrological cycle?
A closed system- it has no inputs or outputs.
What are the common characteristics that most systems share?
They have a structure that lies within a boundary.
They are generalisations of reality, removing incidental detail that obscures fundamental relationships.
They function by having inputs and outputs of material (energy and/or matter) that is processed within the components causing it to change in some way.
Interlocking relationships between the atmosphere, lithosphere, hydrosphere and biosphere…
.. have a profound effect on the Earth’s climate and climate change.
What is atmospheric water?
Water found in the atmosphere; mainly water vapour with some liquid water (cloud and raindrops) and ice crystals.
What is cryospheric water?
What is cryospheric water?
The water locked up on the Earth’s surface as ice.
What is oceanic water?
The water contained in the Earth’s oceans and seas but not including such inland seas as the Caspian sea.
What is terrestrial water?
This consists of groundwater, soil moisture, lakes, wetlands and rivers.
Why does oceanic water taste salty?
Why does oceanic water taste salty?
It contains dossolved salts.
The salt in oceanic water allows what to happen?
Allows the waters to stay as liquids below 0°C.
What pH do the salts in oceanic water have?
What has happened to this pH over time?
What is this linked to?
pH of about 8.14 (so they are alkaline).
Over the past 250 years, the pH has fallen and seems destined to continue falling.
This change in pH is linked to the increase in atmospheric carbon and may have a profound influence on marine ecosystems.
What are the locations of cryospheric water?
Give examples.
Sea ice, eg. the Ross Ice Shelf Ice caps, eg. the Iceland ice cap Permafrost, eg. the Alaska North Slope Alpine glaciers, eg. Mer de Glace, France Ice sheets, eg. the Greenland ice sheet.
How does the magnitude of permafrost vary over time?
Over recent years, it has begun to melt and the amount of permafrost on the Earth has reduced.
How does the magnitude of permafrost vary over space?
Found beneath ice-free regions of the Antarctic continent
Also beneath areas in which the ice sheet is frozen to its bed
How has the magnitude of glaciers varied over time?
Sensitive to seasonal climate fluctuations; shrink in summer (providing melt water to local communities) and advance in winter months.
However, since the 2000 the melting of mountain glaciers has accelerated.
How does the magnitude of glaciers vary over space?
Found in deep valleys or upland hollows, mainly around the Arctic Ocean and nearby lands, such as in Greenland
Can be found on any continent, but mainly mountainous and polar regions
Particularly important in the Himalayas
How has the magnitude of ice caps varied over time?
In recent years, the magnitude of ice caps has been rapidly decreasing
For example, Africa’s only remaining ice cap, on Kilimanjaro is rapidly melting and may soon disappear.
How does the magnitude of ice caps vary over space?
Found in mountainous regions of the World; centred over the highest point of an upland area.
Occur all over the world; Himalayas, the Rockies, the Andes and the Southern Alps of New Zealand.
How does the magnitude of ice sheets vary over time?
Over thousands of years, the snow piles up creating thicker and denser ice sheets
Over time, parts of ice sheets are also lost to the sea; as long as it accumulates the same mass of snow it loses to the sea, it will remain stable
However, the general trend over recent years has been that ice sheets are losing more snow to the sea than they are accumulating.
For example, the Greenland Ice Sheet has been increasing negatively since 1995.
How does the magnitude of ice sheets vary over space?
Two major ice sheets are located in Greenland and Antarctica
Greenland Ice Sheet extends about 1.7million km3
Antarctic Ice Sheet extends about 14million km3