Radiative Transfer in Stochastic Atmospheres
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**Session 7 -- Radiative Transfer and Opacities**
*Display presentation, Monday, 9, 1995, 9:20am - 6:30pm*

## [7.02] Radiative Transfer in Stochastic Atmospheres

*Y. Gu (National Solar Observatory), C. Lindsey, J. T. Jefferies (Solar Physics Research Corp.)*
We describe a general statistical perspective for the study of radiative
transfer through inhomogeneous media and apply it to simple stochastic
atmospheric models. The particular context for our applications considers
a stochastic atmosphere to be a multi-component medium in which any
individual component of the medium is locally smooth. The stochastic
nature of the atmosphere resides in the statistical character of the
complex network of boundaries that separate various species of media one
from another.
We illustrate the theory with simple atmospheric models based on an
ambient medium into which are randomly embedded structural elements
containing alternative species of medium.
We consider structures of various shapes and sizes, ranging from simple
spheres to elongated or fluted structures with preferred orientation.

An important distinctive quality of a stochastic atmosphere is whether
the medium contains structures that individually may be optically thick.
Atmospheres containing only optically thin structures tend to be
statistically amenable to representation by equivalent smooth atmospheres.
The theory we have developed is fully applicable to atmospheres that
contain optically thick elements as well as optically thin ones.
Such conditions apply to a broad variety of radiative transfer problems
in astrophysics and stellar physics, for example, to emission from
interstellar gas clouds, from solar or stellar chromospheres or from
photospheres that contain heated magnetic flux tubes.

In this work we concentrate on a formalism that rests on the Markov
assumption, which states that the probability of encountering a transition
from one type of medium, $A$, to another, $B$, is independent of the
cumulative distance since the transition into medium $A$, as one proceeds
along the optical path.
We examine the importance of this assumption and its utility as a first
approximation by illustrating the consequences of its application to
atmospheric models that are non-Markovian.

**Monday
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