Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Behavior of the reflection function of a plane-parallel medium for
  directions of incidence and reflection tending to horizontal directions   The atmospheres of (exo) planets and moons, as well as reflection nebulae,
contain in general independently scattering particles in random orientation and
are often supposed to be plane-parallel. Relations are presented for the
(bidirectional) reflection function and several related functions of such a
medium in case the directions of incidence and reflection both tend to
horizontal directions. The results are quite general. The medium may be
semi-infinite or finite, with or without a reflecting surface underneath, and
vertically homogeneous or inhomogeneous. Some approximative formulae for the
reflection function of a plane-parallel medium with independently scattering
particles in random orientation, including Lambert's law, may be very
inaccurate if the directions of incidence and reflection are both nearly
horizontal.

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The categories of this paper are: eess
1
The categories of this paper are: cs
18
The categories of this paper are: econ
29
The categories of this paper are: funct-an
5
The categories of this paper are: gr-qc
35
The categories of this paper are: mtrl-th
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
8
The categories of this paper are: hep-ex
0
The categories of this paper are: hep-ph
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
22
The categories of this paper are: chao-dyn
2
The categories of this paper are: math
4
The categories of this paper are: cond-mat