1.3 Energy and Equilibrium Flashcards
(26 cards)
1st Law of Thermodynamics
Energy in an isolated system and is neither created nor destroyed, only changes forms.
2nd Law of Thermodynamics
the entropy of an isolated system, not in equilibrium, will tend to increase over time. this reduces amount available to do work.
Entropy Definition
The measure of disorder in a system.
Entropy is simply a quantitive measure of what the 2nd law describes: dispersal of energy in a process of our material world.
Entropy explanation
Increase of entropy from energy transformations = Reduces energy available to do work
1st Law of Thermodynamics represented in a Food Chain + Energy Production System
Solar energy → absorbed by plants → made into chemical energy → plants eaten by animals & used for energy
2nd Law of Thermodynamics represented in a Food Chain + Energy Production System
When one animal feeds off another → loss of heat (energy) in respiration and movement
More and more energy is lost as one moves up trophic levels
Inefficiency/decrease in available energy along the food chain
Steady-State equilibrium definition
occurs in open systems where there are countinous inputs and outputs of energy and matter, but the system as a whole remains in a more or less constant state. there are no long term changes but there may be small fluctuations in the short term.
Stable equilibrium definition
The tendency in a system for it to return to a previous equilibrium condition following disturbance.
Static equilibrium definition
Occurs when there is no change over time.
When it is disturbed, it either returns to equilibrium (stable) or adopts a new equilibrium (unstable)
Resilience definition + explanation
The ability of a system to return to its initial state after how a system responds to a disturbance.
The MORE resilient a system → the MORE disturbance it can deal with
e.g. in agriculture, we want stability so we can predict that the amount of food we grow is about the same each year. If this does not happen, it can lead to famine.
Factors that can increase resilience (8)
- higher temps, light+water availability, resulting in faster growth rates: tropical rain forest
- greater genetic diversity
- greater species diversity
- reduce an invasive species
- less pollution
- faster rate of reproduction (r-strategist)
- large ecosystem
- spread over a large geographical energy
Tipping points definition
Small changes in systems that tip the equilibrium over a threshold, potentially transforming into a very different system.
- changes that are hard to reverse
- long-lasting changes
- involve positive feedback
Tipping points real life example
River Eutrophication
- rain washes fertilisers from farmers fields into rivers
- extra nutrients result in excessive plants growth
- light is blocked by decomposing plant material
- oxygen levels fall + animals die
- river becomes eutrophic + takes great effort to restore
Negative feedback loop definition
Stabilises steady-state equilibrium by neutralising any deviation from an equilibrium. It results in self-regulation of a system.
Negative feedback loop example
Predator-Prey model
- When prey populations (hare) increases, there is more food for predators (lynx) so they eat+breed more predators which eat more prey so that prey numbers decrease
Positive feedback loop definition
Destabilises steady-state equilibria and pushed to a new state of equilibrium. It speeds up the input until the system collapses.
‘Vicious cycle’ ↔ disequilibrium
Positive feedback loop example
Global Temperatures rise, causing ice caps to melt. Dark soil is exposed, so more solar radiation is absorbed → reduces albedo of Earth so global temperatures rise + cycle keeps going.
Albedo definition
The amount of light reflected by a surface.
Systems at threat from tipping points
- Antarctic sea ecosystem
- Amazon Rainforest
- Greenland ice sheet
POSITIVE Human Impact on Resilience of Systems
Humans can remove or mitigate threats to the system (pollution, invasive species) — resulting in faster recovery/more resilience
NEGATIVE Human Impact on Resilience of Systems
- Reducing diversity: Hunting animals for pets, e.g., removal of fish from the tropical reefs.
- Reducing the size of the storages: Deforestation of tropical rainforests in Indonesia.
- Climate change: Over-abstraction of surface water worsens the problems of extreme weather (e.g., drought) caused by climate change.
Delays in Feedback Loops effect+explanation
Make it difficult to predict tipping points and add to the complexity of modelling systems.
Not all components or processes within a system will change abruptly at the same time
Delays in Feedback Loops real life example
Activities in one part of the globe may lead to a system reaching a tipping point elsewhere on the planet (e.g. the burning of fossil fuels by industrialised countries is leading to global warming, which is pushing the Amazon basin towards a tipping point of desertification) - continued monitoring, research and scientific communication is required to identity these links
Equilibirum
A state of balance among the components of a system.
