Wes wrote:
I don't give a damn what they call it, here's a definition of
precipitation:

precipitation n. a: a deposit on the earth of hail, mist, rain, sleet
or snow: also: the quantity of water deposited.

I don't see anything about dirt.

As you know, words often have a different technical
meaning than their common Webster's dictionary meaning.
The adjective "precipitation" modifying "static" or
"noise" has been extended to dust as well as rain or
snow, just as the p-static definition indicates.

Airplanes flying through rain, snow, and dust exhibit
the same physical phenomena so dust has been included
as one of the causes of precipitation static. A web
search will prove that to be true. Example quotes:

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Volume 2, Issue 4 (December 1945)
Journal of the Atmospheric Sciences

Article: pp. 205–213 | PDF (801K)
METEOROLOGICAL ASPECTS OF PRECIPITATION STATIC

Robert C. Edwards, Lieutenant U.S.N.R. and George W. Brock,
Captain U. S. A. A. F.

ABSTRACT

*Precipitation static*, a result of electrification of aircraft
in flight, can cause loss of radio communication for long periods
of time. Electrification may consist of either of two types,
“autogenous” or “exogenous” electrification; autogenous electrification
occurs when snow, *dust* or rain strike the surface of the aircraft,
while exogenous electrification results from an aircraft being placed in
a pre-existing atmospheric electric field. Serious autogenous
electrification occurs only in snow and *dust* storms; ...

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Please note the date. Precipitation static from dust has been
recognized for more than half a century. There are many more
references available. One advertisement asks the following
question:

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Ads by GoooooogleMicro Air *Dust* Collectors
Tired of cleaning electrostatic *precipitator* cells?
www.microaironline.com

************************************************** ************

SAE Technical Papers
Title: *Precipitation-Static* (P-Static) Overview of Composite
Aircraft, Document Number: 2001-01-2933

Author(s):
Jerry W. Thornell - The Boeing Co.

Abstract:
Aircraft charging due to *p-static* results from two atmospheric
conditions: 1) the vehicle's presence in a thunderstorm, and 2)
the triboelectric charging (frictional) caused by neutral snow,
rain, or *dust* particle bombardment of the vehicle frontal surface.

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Development of Transparent Materials Which Reduce Effects of
*Precipitation Static* in Aircraft
Authors: M. U. Cohen; George A. Dalin; BALCO RESEARCH LABS NEWARK NJ

Abstract: Methods of laying a transparent electrically conductive
film on plastic airplane canopies are discussed. The purpose of
such films is to conduct to the aircraft frame the static charges
developed on the canopies by friction with air, *dust*, snow, etc.,
during flight.

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From: http://www.faa.gov/ATpubs/AIM/Chap7/aim0705.html

7-5-11. Precipitation Static

a. *Precipitation static* is caused by aircraft in flight coming in
contact with uncharged particles. These particles can be rain, snow,
fog, sleet, hail, volcanic ash, *dust*; any solid or liquid particles.
--
73, Cecil http://www.w5dxp.com