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.
Positive or negative feedback can be triggered by..?
A change in the system.
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:
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:
What are the major subsystems of the water system?
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?
What percentage of fresh water is found in groundwater?
What percentage of fresh water is found in lakes?
What percentage of fresh water is found in soil moisture?
What percentage of fresh water is found in the atmosphere?