### plane-parallel atmosphere

(simplified atmosphere model ignoring its curvature around the body)

A **plane-parallel atmosphere** is a model atmosphere that ignores
the curvature of the underlying body, i.e., is dealt with as if it
is planar/flat. Such models are used in meteorology (Earth or other
bodies) and for stellar models. They are especially suitable for
(spherical) bodies where the atmosphere is a relatively thin layer around
the body, i.e., "locally, virtually flat". Their use is typical in
1D models.

Perhaps the primary simplification is that when dealing with lines
at an angle, i.e., neither vertical nor horizontal to the surface,
the lines are treated as if the atmosphere is flat. For example, when
calculating the effects of a beam
of light passing through at such
an angle, the light is treated as if it is passing through flat,
parallel layers, any effects of the atmosphere-layer's
curvature ignored.

Use of the plane-parallel atmosphere makes models easier, often
making the difference in the model's practical tractability. This
is true both to analytic models and computer simulations.

(*atmosphere,stars,planets,weather*)
**Further reading:**

http://en.wikipedia.org/wiki/Model_photosphere

http://glossary.ametsoc.org/wiki/Plane_parallel_atmosphere

https://www-zeuthen.desy.de/~pohlmadq/teach/405-505-f07/sess7.pdf

**Referenced by pages:**

gray atmosphere

photosphere

plane wave

equation of radiative transfer (RTE)

stellar structure

Index