The "World's Most Popular GPS Information Resource," in the guise of
GPSInformation.net, has all sorts of information on Global Positioning
Systems (GPS) which covers satellite navigations systems.
One would imagine that such a resource would cover your question and
they do just that.
"Rain, Snow, Clouds and GPS Reception"
"... Does RAIN or SNOW or CLOUDS affect the reception of my GPS receiver?
Answer: No. Not so as the user can tell without instrumentation.
Cloud, Rain, Snow, weather in general does NOT attenuate the GPS signals
enough to effect accuracy. As can be seen below, the total atmospheric
loss (from all causes including rain, clouds, snow, fog, etc.) is but 2db.
This is small compared with other variables."
The above page has a table of power levels that might interest you. It
also references a technical paper on signal specifications that you might
want to read.
"GPS SPS Signal Specification, 2nd Edition (June 2, 1995)"
"GPS SPS Signal Specification - Main Document"
"GPS SPS Signal Specification - Annex A thru C"
If you need any clarification, please feel free to ask.
Google search on: rain affect satellite navigation
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