Heat radiation (as opposed to particle radiation) is the transfer of internal energy in the form of electromagnetic waves. For most bodies on the earth, this radiation lies in the infrared region of the electromagnetic spectrum.
One of the first to recognize that heat radiation is related to light was the English astronomer William Herschel, who noticed in 1800 that if a thermometer was moved from one end of a prism produced spectrum to the other, the highest temperatures would register below the red band, where no light was visible. Because of this position, this form of radiation is called infrared (infra being the Latin word for below or within). Sometimes this kind of radiation is called "heat waves" but this is a misnomer. Recall that heat is the transfer of internal energy from one region to another. As all forms of electromagnetic radiation transfer internal energy, they could be called heat.
Φ = εσA(T4 − T04)
where σ [sigma] is called Stefan's constant, which was discovered experimentally by Josef Stefan (1835-1893) Austria in 1879 and ε [epsilon] is the emissivity.
|σ =||2π5k4||=||π2k4||= 5.67 × 10−8 W/m2K4|
Disconnected thoughts that aren't quotes.
|Dark colors absorb more radiant energy than do light colors. The burns on this woman's skin mimic the pattern on her blouse. She was exposed to a monstrous dose of electromagnetic radiation from a nuclear blast. (Source: Unknown)|
A more complete explanation of this law can be found in the section on Planck's law.
where x is the solution of
|xex||− 5 = 0|
|ex − 1|
x = 4.96511…
In shortened form
b = 2.898 … mmK
|radiant energy source|
|2.73||cosmic background radiation|
|500||household oven at its hottest|
|660||minimum temperature for incandescence|
|770||dull red heat|
|1400||glowing coals, electric stove, electric toaster|
|2800||incandescent light bulb, 75 W|
|2900||incandescent light bulb, 100 W|
|3000||incandescent light bulb, 200 W|
|3100||sunrise or sunset (effective)|
|3200||professional studio lights|
|3600||one hour after sunrise or one hour before sunset (effective)|
|4000||two hours after sunrise or two hours before sunset (effective)|
|5500||direct midday sunlight|
|7000||overcast sky (effective)|
|color||T (K)||class||discrete spectra||examples|
|very blue||30,000||O||He+, N++, Si+++,
other highly ionized atoms
He, Si+, Si ++, O+, Mg+
Mg+, Si+, Fe+, Ti+, Ca+
|yellow-white||8000||F||weak H; Ca+, Fe+, Cr+; Fe, Cr,
and other neutral metals
|yellow||6000||G||strong Ca+; many neutral
and ionized metals; CH bands
|sun, alpha centauri|
|red||3000||M||molecular TiO bands;
The basic effect…
Global temperature and atmospheric carbon dioxide trends match. The very long graph made popular by Al Gore in An Inconvenient Truth.
Plot one against the other. The relation is approximately linear. Al Gore never did this one.
Naturally occurring greenhouse gases whose concentrations are increasing due to human activities
Other naturally occurring greenhouse gases of lesser concern.
Greenhouse gases that do not occur naturally.
Indirect greenhouse gases
key infrared absorption bands in the atmosphere correspond to H2O, CO2, O3
(CO2 = 1)
|Sources:||IPCC and others||*||trifluoromethyl sulphur pentafluoride|
Temperatures are rising across the globe.