Heat and Energy LEC Part 2

Conduction

Heat transfers by CONTACT & MOLECULAR MOTION (directly from molecule-to-molecule) from warm objects (high-energy) to cold objects (low energy). Larger temperature difference → more rapid heat transfer.

Does not

Still air [DOES/DOES NOT] conduct air well.

Convection

Heat energy transferred through vertical mass movement of a fluid (liquid or gas).

thermals, rise, fall

In convection, warm, less dense fluids— called [TERMS] — [TERM] while cooler, less dense fluids [TERM]

radiation

type of heat transfer through EM waves by emission, absorption, reflection, scattering, and transmission.

conductive

Thunderstorm cells are [TERM] because they rely on strong thermals (hot, rising air) and moist air.

Thermals, convection

[TERMS] form because air is heated by contact with the surface (conduction). A hot, less dense parcel of air near the ground rises and generates turbulent motion. Atmospheric [TERM] is much more efficient at spreading heat over long distances.

0, radiation

All objects with a temperature greater than [#]K emit [TERM].

Stefan-Boltzmann Law

Describes the relationship between an object’s temperature and the radiation it emits by the power of 4. In short, a slight change in temperature leads to a large increase in emitted energy.

E=(5.67×10^-8 W/m²K^4) x T^4

Write the Stefan-Boltzmann Law. Include the constant.

EDIT: WIEN’S LAW

EDIT: Describes the relationship between radiation and maximum wavelength (the wavelength where an object emits the largest amount of radiation).

visible

The sun’s radiation peaks in [TERM] wavelengths.

infrared

Earth’s radiation peaks in [TERM] wavelengths.

Blackbody

This type of material is a perfect absorber, absorbing all incident radiation, and a perfect emitter, emitting the maximum radiation possible at a given temperature

is not, selectively, all

The atmosphere [IS/IS NOT] a blackbody because it [TERM] absorbs long-wave radiation (LWR). Blackbodies absorb [TERM] incident radiation.

Kirchoff’s law

States that any object that selectively absorbs radiation at a particular wavelength tends to re-emit radiation at that same wavelength. Good absorber= good emitter.