Black body temperature

Total Radiation Pyrometers In total radiation pyrometers, the thermal radiation is detec ted over a large range of wavelengths from the objec t at high temperature. The detector is normally a thermopile, which is built by connec ting several thermocouples in series to increase the temperature measurement range. The pyrometer is calibrated for black bodies, so the indicated temperature Tp should be converted for non-black body temperature. 

The development of new low-temperature detection technology and the launch of the Cosmic Background Explorer (COBE) satellite by NASA in 1989 helped to resolve this problem. The results from these observations were amazing - an almost perfect black body curve (Figure 2.3) with a black body temperature of 2.725 0.002 K and a maximum wavelength of the radiation at kmax = 1.05 mm. 

The Balmer series is seen in many but not all stars because the first energy level in the series is an excited state with quantum number n = 2. There has to be a mechanism by which the excited stated is populated and this is the local temperature of the star. Hence only if the star is sufficiently hot will the spectrum contain the Balmer series. The strength of the Balmer series within the stellar spectrum can be used to derive a temperature for the surface of the star to compare with black body temperature and the B/V ratio. 

Calculations Black body temperature Radiodating Chemical networks on comets Temperatures of meteors and meteorites on entry Estimate of the age of a rock from the radioisotopes Extension of the idea of networks in the interstellar medium to molecular processing on the surface of comets... 

The preceding calculation of the thermal energy balance of a planet neglected any absorption of radiation by molecules within the atmosphere. Radiation trapping in the infrared by molecules such as CO2 and H20 provides an additional mechanism for raising the surface temperature - the greenhouse effect. The local temperature of a planet can then be enhanced over its black body temperature by the atmosphere. 

Cosmic microwave background radiation Fossil radiation surviving form the Big Bang with a black body temperature of 2.725 K. 

Rubincam D. P. (2004). Black body temperature, orbital elements, the Milankovitch precession index, and the Seversmith psychroterms. Theoretical and Applied Climatology, 79(1-2), 111-131. 

We often measure the temperature of solid or liquid substances at high temperature by comparing them with the brilliancy or colour of the black body. This value does not show the true temperature of the substance, but this method is quite favourably used because we have no other simple method like this. The temperature which is measured by the comparison with the brilliancy of the black body is called black body temperature or brightness temperature, and with the colour of the black body colour temperature. 

The Earth is warmer than surrounding space, so it radiates energy back into space, at wavelengths dictated by its black-body temperature (c.255K, or -18°C). The relatively low surface temperature... 

The extravagent claim that only big-bang synthesis can account for the relative abundances of H and He is based on a chain of assumptions, long enough to predict any desired result. The logic of the (a — / — 7) scheme depends on the assumed relationship between black-body temperature and the radius of the expanding universe... 

The first reaction is rate determining and depends on temperature and matter density. It becomes a race against the expansion of R t) and depends critically on the value of s at f = 700s. Being independent of T this value of s predicts the black-body temperature today, at a particle density of lO cm", i.e. 

Such considerations brought the He/H ratio closer to the experimentally most likely value of 1/11, without lowering the black-body temperature. The cooling rate of the big-bang universe has defeated all efforts to demonstrate the primeval production of heavy elements, which is now accepted to occur in massive stars. The problem is that these same processes also produce large quantities of He, which, added to the big-bang production, far exceeds the theoretical budget (Lerner, 1989). 

In the test, 460-mm long (1.5-ft) long, 150-m (0.5-ft) wide and up to 25-mm (1-inch) thick vertical polymer sample is used. The vertical polymer sample is placed at an angle in front of a 460-mm (1.5-ft) x 300-mm (1-ft) radiant panel. The top of the polymer sample is closer to the radiant panel, forcing the ignition near its upper edge and the flame front to progress in the downward direction. The maximum output of the radiant panel is equivalent to a black body temperature of 670 4°C (45 kW/m ). The measurements made in the test consist of ... 

The ATCOR program used for estimation of the LST assumes two surface temperatures Tj and with their corresponding black body temperatures T, and... 

From Planck s radiation formula, other relationships for a black body spectrum can be derived. The Stefan Boltzmann law gives the total radiance emitted (pbb) black body as a function of the black body temperature ... 

Figure 2 is a color-color diagram [J — H vs. H — K) for all the sources in the table except for H5W which was undetected in J. A reddening vector from zero intrinsic colors is plotted along with an unreddened locus of black body colors the black body temperature is labelled for some points. The... 

Fig. 2. Color-color diagram of HI, H2, and H5, regions. A reddening vector om zero intrinsic colors is plotted along with the locus of unreddened black body colors where the black body temperatures are labeled.

---