Evaluation II – The Atmosphere Feedback describes the situation when output from (or information about the result of) an event or phenomenon in the past will influence the same event/phenomenon in the present or future. When an event is part of a chain of cause-and-effect that forms a circuit or loop, then the event is said to "feed back" into itself. Feedback: the process in which part of the output of a system is returned to its input in order to regulate its further output Feedback: the process by which a system, often biological or ecological, is modulated, controlled, or changed by the product, output, or response it produces.

TOA surface Ts R: earth’s radiation budget (net solar in S – net infrared out OLR α: planetary albedo R = 0 at equilibrium With external perturbation (e. g., increase CO 2 ) radiation budget out of equilibrium by ΔQ, radiative forcing to which climate responds by a change in global mean surface ΔT s, which can be related to forcing and imbalances at TOA by where λ is the feedback parameter. New equilibrium  ΔR = 0. (+) Basic definition of feedback

H2OH2O CO 2 CH 4 O 2, O 3 N2ON2O Total ~400 nm ~700 nm Visible Range Spectrum of the Sun’s Incoming Radiation

Spectrum of the Earth’s Outgoing Radiation

Major feedbacks at work in the Earth’s climate system: Water vapor feedback Clouds feedbacks IR flux –Temperature Feedback Aerosol feedback Snow/Ice-albedo feedback Ocean circulation feedback Biosphere feedback See also Page 4 of Reading Notes on Atmosphere, particularly the diagram on that page showing the loop that constitutes a feedback.

Examples of feedbacks that include the land-atmosphere coupling (This below also applies to help explain diagrams in question 4). More High Cloud --> Warming More Low Cloud --> Cooling Warming --> Evaporation