Sep 16 Energy, Radiation, and Climate System: Key Vocabulary

Flashcards cover fundamental energy concepts, radiation, and the Earth’s energy budget as discussed in the lecture notes.

Energy

A quantitative property of matter that has magnitude and can be transferred; manifests as work, heat, or light.

Heat

The transfer of thermal energy from a region of higher temperature to one of lower temperature.

Thermodynamic Equilibrium

A state where energy entering a system equals energy leaving it, so internal energy (and temperature) remain constant.

Conduction

Energy transfer through direct contact within or between materials due to a temperature difference.

Convection

Energy transfer through bulk movement of fluids (gases or liquids) within the system.

Radiation

Energy transfer by electromagnetic waves, which can occur through vacuum without a medium.

Black Body

An idealized object that absorbs all incident radiation and re-emits energy maximally; used as a reference for radiation.

Photon

A quantum particle of light that carries energy and explains the particle-like behavior of electromagnetic radiation.

Wavelength

Distance between successive peaks of a wave; longer wavelength means lower frequency, shorter wavelength means higher frequency (for a given speed).

Frequency

Number of wave cycles per second; inversely related to wavelength when the speed of light is constant.

Speed of Light

Constant c ≈ 3.0 × 10^8 m/s in vacuum; relates wavelength and frequency via c = fλ.

Stefan–Boltzmann Law

Total radiant energy emitted per unit area is proportional to the fourth power of absolute temperature (E ∝ T^4).

Emissivity

Efficiency with which a body emits radiation (0–1); sun ≈ perfect emitter, Earth ≈ less than perfect.

Albedo

Reflectivity of a surface; fraction of incoming radiation reflected back, affecting energy absorbed.

Solar Constant

Average solar energy received per unit area at Earth's orbit (≈ 1368 W/m^2).

Greenhouse Effect

Atmosphere absorbs infrared radiation and traps heat, leading to a warmer surface than a bare planet.

Equilibrium Temperature

Temperature at which incoming solar energy equals outgoing energy; determines the planet’s mean surface temperature.