Earth's Warming and Energy Transfer

Flashcards covering Earth's energy balance, temperature scales, methods of heat transfer (conduction, convection, radiation), and the greenhouse effect based on the lecture transcript.

Temperature

A measure of the average motion or speed of atoms within a substance, also defined as the measure of average kinetic energy.

Celsius

A temperature scale where the freezing point of water is $0^\circ\text{C}$ and the boiling point of water is $100^\circ\text{C}$ at sea level pressure.

Fahrenheit

A temperature scale of human experience where $32^\circ\text{F}$ is the freezing point and $212^\circ\text{F}$ is the boiling point of water.

Kelvin

An absolute temperature scale where $0\,K$ represents absolute zero, the point at which there is no kinetic energy and particles do not move.

Kinetic Energy

The energy of motion; in air, warmer temperatures equate to higher average motion and higher kinetic energy.

Potential Energy

Energy that has the potential to do work but is not actively doing it, such as a bowling ball on top of a building or substance that can be burned.

Energy

The capacity or ability to do work on matter; it changes forms and transfers but cannot be created or destroyed.

Heat

Energy that is in the process of being transferred from one object to another due to differences in temperature.

Conduction

The transfer of heat from molecule to molecule within a substance, such as heat traveling through a metal pin.

Convection

The transfer of heat by a fluid, such as water or air, typically referring to the vertical rising and sinking of air.

Advection

A meteorological term for the transfer of heat or properties via horizontal motion.

Radiation

A form of heat transfer that does not require a substance or medium, traveling in the form of electromagnetic waves at the speed of light.

Stefan Boltzmann Law

A law stating that the amount of radiation an object emits is proportional to the fourth power of its temperature (e.g., doubling the temperature results in $16\times$ more radiation).

Wien's Law

A law stating that the wavelength of maximum radiation emission is inversely proportional to temperature; colder objects emit longer, less energetic wavelengths.

Shortwave Radiation

Radiation primarily emitted by the sun in the visible portion of the spectrum.

Longwave Radiation

Infrared radiation emitted by the Earth, characterized by longer wavelengths and less energy than solar radiation.

Black Body

An object that absorbs all radiation hitting it and emits everything it absorbs; the Sun and the Earth's surface are efficient examples.

Radiative Equilibrium

A state where the amount of incoming solar energy equals the amount of outgoing infrared radiation; for Earth without an atmosphere, this temperature would be $0^\circ\text{F}$ ($255\,K$).

Greenhouse Effect

The process where selective absorbers in the atmosphere absorb outgoing longwave radiation and re-emit it back toward the surface, keeping Earth warm enough for life.

Selective Absorbers

Atoms or molecules, such as greenhouse gases, that absorb radiation only at certain wavelengths and are transparent to others.

Albedo

The measure of a surface's reflectivity; clouds and ice have high albedo, while forests and water have low albedo.