External Forces, Daisyworld, and Radiative Laws - Vocabulary Flashcards

Vocabulary flashcards covering key terms from the lecture notes on external forces, disturbances, Daisyworld, and radiative laws.

External forces

Disturbances that create a response in a system; can be perturbations, forcing, or periodic changes.

Disturbance

An event that pushes a system away from its equilibrium, which may be temporary, persistent, or periodic.

Perturbation

A sudden, short-lived departure from the normal or mean state followed by a return to a new mean.

Forcing

A persistent directional change through time (e.g., gradual slowing of Earth’s rotation or increasing atmospheric CO2).

Periodic change

A change that repeats at regular intervals (e.g., tides, seasonal CO2 variations).

Positive feedback loop

A feedback loop that amplifies disturbances; tends to produce an unstable (unbounded) response.

Negative feedback loop

A feedback loop that diminishes disturbances; tends to produce a stable equilibrium.

Stable equilibrium

A state where perturbations are damped and the system returns toward equilibrium.

Unstable equilibrium

A state where perturbations grow, leading away from equilibrium (positive feedback).

Albedo

The fraction of incoming solar radiation that is reflected by a surface.

Area-average albedo

The mean albedo calculated over a specified surface area.

Daisyworld

A simplified hypothetical planet used to illustrate how biota (daisies) can regulate climate via albedo.

Gaia Hypothesis

Idea that Earth is a self-regulating system in which biota play an integral role.

White daisies

Daisies with high reflectivity (high albedo) that reflect more sunlight.

Optimum growth temperature

The temperature at which daisies grow best, influencing the direction and strength of feedback.

Daisyworld albedo feedback

Feedback loop on Daisyworld where increasing white-daisy coverage raises albedo, lowers temperature, and affects daisy growth.

Planck function

Describes the spectral distribution of radiation emitted by a blackbody at a given temperature.

Blackbody

An object that emits and absorbs all wavelengths with 100% efficiency.

Blackbody radiation

Radiation emitted by a blackbody; its spectrum depends on the object's temperature.

Electromagnetic spectrum

Range of electromagnetic radiation wavelengths from gamma rays to radio waves, including UV, visible, and IR.

Wavelength

Distance between successive wave crests; commonly measured in micrometers (µm) or nanometers (nm).

Wien's Law

λ_max = 2898 µm·K / T; the wavelength of maximum emission is inversely proportional to temperature.

Wien's constant

The constant in Wien’s Law, approximately 2898 µm·K.

Shortwave radiation

Higher-energy, shorter-wavelength radiation, typically solar radiation.

Longwave radiation

Lower-energy, longer-wavelength radiation, typically Earth’s thermal infrared emission.