American Dialect Maps

The fictional character Henry Higgins is an expect of of different British dialects and combination thereof. Here is series of American dialect maps derived a survey of internet users in 2002 put together by some linguists then at Harvard. Although it is a billed as a survey of "North American English" only the locations of American participants are mapped. The survey has asks participants questions of pronouncement and usage. The map above is one map for the question "What do you call it when rain falls while the sun is shining?".

Personally, I heard/read of liquid sun(shine) as a metaphor for nuclear fire.