Water Cycle Flashcards
What is the difference between an open and closed system?
Open systems - both energy and matter CAN enter and leave the system (e.g. drainage basin)
Closed system - MATTER CAN’T enter and leave, but ENERGY CAN (e.g. carbon cycle)
What is dynamic equilibrium?
A system is in a dynamic equilibrium when the inputs and outputs of a system are balanced
How is positive and negative feedback triggered?
Large long term changes to the balance of inputs and outputs cause a system to change and establish a new dynamic equilibrium. Changes can trigger positive/ negative feedback.
What is positive feedback?
Amplifies the change in inputs and outputs
The system responds by increasing the effects of change, moving the system even further away from its previous state
What is negative feedback?
Counteracts the change in inputs and outputs
System responds by decreasing the effects of change, keeping the system closer to its previous state
Give an example of a positive feedback system
Temps rise
Ice melts due to ^temps
Less ice cover = less of suns energy reflected
Less energy reflected = more absorbed by earth
Temps rise
Give an example of a negative feedback system
Lots of CO2 emitted CO2 in atmosphere increases ^CO2 causes plants to grow more Plants remove CO2 from atmosphere CO2 in atmosphere reduces
What are the subsystems of the earth system?
Cryosphere Lithosphere (crust and upper mantle) Hydrosphere Atmosphere Biosphere
What type of system is the Earth system?
A cascading system
Changes in one system can effect what happens in others
How much water does the hydrosphere contain? How much of this is fresh water?
1.4 sextrillion litres of water
Less than 3% water
What is the make up of the earths fresh water?
69% cryosphere
30% groundwater
0.3% liquid fresh water
0.04% water vapour in the atmosphere
How come only a small amount of the water in the hydrosphere can be used?
What’re must be physically and economically accessible to humans for them to be able to use it.
What type of system is the global hydrological cycle?
Closed system
Water is continuously cycled between different stores
What is evaporation?
When liquid water changes state to gas, becoming water vapour.
^amount if water in atmosphere
Magnitude of evaporation varies by location and season
What is condensation.
When water vapour changes state to become a liquid
Air containing what’re filled to dew point
Magnitude of condensation depends on…
Amount of water vapour in atmosphere
Temperature
How do clouds form?
Clouds form when warm water cools down, causing the water vapour in it to condense into water droplets, which gather as clouds
Cloud formation and precipitation varies seasonally and by location
How does frontal precipitation form?
When warm air meets cool air, the warm air is forced up above the cool air. It cools down as it rises = frontal precipitation
How does orographic precipitation form? (Relief rainfall)
When warm air meets the mountains it is forced to rise, causing it to cool
How does convective precipitation form?
When the sun heats up the ground, moisture on ground evaporated and rises up in a column of warm air. As it gets bigger it cools = convective precipitation
Water droplets caused by condensation are too small to form clouds by themselves, so therefore…
There needs to be tiny particles other other substances to act as CLOUD CONDENSATION NUCLEI.
These give the water molecules something to condense on.
How do cryospheric processes change the amount of water stored in the cryosphere?
Accumulation and ablation.
The balance of the two varies with temperature
What happens to crysopheric processes in a period of global cold?
Inputs are greater than outputs. Vice versa when hot.
Earth emerging from glacial period that reached its max 2100 years ago
How do variations in cryospheric processes happen over different time scales?
Global temperature change occurs over 1000s of years
Also annual temperature fluctuations
What is the drainage basin?
The area surrounding the river where rain falling on the land flows into the river
Boundary of drainage basin = watershed
