Please Explain Why the answers are Positive or Negative Feedback Loop. I don\'t

Question

Please Explain Why the answers are Positive or Negative Feedback Loop. I don't quite understand.

Answer is: Positive Feedback Loop.

2)

Answer: Negative Feedback Loop

In the diagram shown above arrows represent a positive coupling and lines attached to open circles represent a negative coupling A positive coupling is when change (increase or decrease) in one component stimulates a change in the same direction in the linked component. A negative coupling is when a change in one component stimulates a change of the opposite direction in the linked component. With this in mind, the diagram above represents.

Explanation / Answer

(a) A positive feedback loop happens when change in a quantity further causes the change in the same direction in that quantity(i.e an increase leads to further increase and a decrease leads to further decrease) via some mechanism.

Suppose surface temperature decreases, this will cause snow cover to increase (obviously), this in turn will increase the albedo(more sunlight will be reflected), which in turn will further decrease the temperature.

The same logic can be applied to an increase in surface temperature.

(b) A negative feedback loop happens when change in a quantity causes the change in the opposite direction in that quantity(i.e an increase leads to a decrease and a decrease leads to an increase) via some mechanism.

Suppose surface temperature increases, this will cause the glacial ice to melt and hence decrease, which in turn will provide territory for biomass to survive, which in turn will decrease the atmospheric CO2 levels, which in turn will decrease the temperature.

The same logic can be applied to a decrease in surface temperature.

As a rule, any loop with an odd number of negative couplings with any number of positive couplings will be a negative feedback loop.

any loop with an even number of negative couplings with any number of positive couplings will be a positive feedback loop.

Let me know if anything is unclear.

Cheers,

Saurav

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