brightness temperature


Also found in: Acronyms, Wikipedia.

brightness temperature

In radio astronomy, a source of surface brightness (i.e., flux density per unit solid angle) B has a brightness temperature of T B = B λ2/(2k ), where λ is the observing wavelength and k is the Boltzmann constant. If the source of that radiation is a black body, and the observing wavelength sufficiently long, the brightness temperature will equal the temperature of the black body. In the case of an interstellar cloud, it may equal the physical temperature of the cloud if the radiation is by thermal emission and the cloud is optically thick (see optical depth). If the cloud is optically thin, the brightness temperature is reduced.

Sources that radiate by nonthermal emission can have very high brightness temperatures (>109 K). See also antenna temperature.

brightness temperature

[′brīt·nəs ‚tem·prə·chər]
(thermodynamics)
References in periodicals archive ?
For accurate retrievals of wind speeds when precipitation is present it is essential to use different frequencies, whose spectral signatures make it possible to find X- and C-band channel combinations that yield brightness temperature with sufficient sensitivity to wind speed and low sensitivity to rain (Shibata 2006; Yueh 2008; Meissner and Wentz 2009; El-Nimri et al.
By calculating the IFT of the visibility function samples, a brightness temperature image could be obtained in the computer.
Radio measurements of brightness temperatures are also highly dependent on wavelength and scattering processes (see e.
For the secondary reflection ray, the sky brightness temperature reflected by the metal target surface firstly arrives at the ground, and then is reflected into the antenna through the smooth surface; meanwhile the radiation energy of the ground itself also enters into the antenna, so the radiation temperature can be expressed as:
The modified brightness temperature could be expressed as
The equipment, provided by Japan's National Space Development Agency, picks up both sea surface and brightness temperatures.
Three sources of apparent brightness temperature play an important role in determining the PMMW antenna temperature that will be observed by a low-altitude, earth terrain sensor.
Total measured brightness temperatures are divided into M groups of [tau] seconds each, and the Allan variance is one half of the mean square error between contiguous averages brightness temperature ([T.
Accordingly, there is no reason to expect that brightness temperatures in the second setting will be correct.