Chapter 3 Flashcards
Open system
Not generally contained without boundaries
Energy or material moves into or out of the system
System
A set of components or parts that function together to act as a whole
Components may themselves be systems (subsystems)
Systems respond to inputs and have outputs
Closed system
No such movements take place ( there are few pure closed systems)
Dynamic equilibrium
The steady star that all natural systems move towards wight influence of people
Seldom attained or maintained very long
Steady state
A dynamic equilibrium
Material of energy is entering and leaving the system in equal amounts
Opposing processes occur at equal rates
Average residence time
The time it takes for a given part of he total reservoir of a particular material to be cycled through the system
The equation for average residence time is : ART= size/rate of transfer
Positive feedback
Output of the system also acts as input Leads to further change n the system Vicious cycle (destabilizing)
Negative feedback
System's response is in the opposite direction to the output Self regulating (stabilizing)
Exponential growth
Growth occurs at a constant rate per time period
N=Noe^kt
Doubling time
The time necessary for the quantity being measured to double
Approximately equal to 70!divided by the annual percentage growth rate
Environmental problems and exponential growth
The consequences of exponential growth and it’s accompanying positive feedback can be dramatic
Environmental problems and lag time
The time between a stimulus and the response of a system
If there is a long delay between stimulus and response, the. The resulting changes are much more difficult to recognize.
Environmental problems and irreversible consequences
Consequences that may not be easily rectified on a human scale of decades of a few hundred years
Environmental unit
Everything effects everything else
Earth and it’s ecosystems are complex entities in which any action may have numerous effects
Uniformitarianism
Process that operate today operated in the past
Observations of processes today can explain events that occurred in the past and left evidence
The present is the key to the past
The study of past and present processes is the key to the future
