The article "a/an" with uncountable nouns

Sometimes I read in books sentences where uncountable nouns are used with the article "a/an". For example

She fades like a dew before the sun.

Is it out of the common rules?

Sorry if this question seems to be stupid. I'm just trying to figure out all the usages of the articles that I don't fully understand.

Certainly, ‘dew’ is normally uncountable, but the writer precedes it here with the indefinite article for literary effect. Other meteorological phenomena, such as fog and mist, can be treated in the same way. It's not at all a stupid question.

We sometimes put 'a' or 'an' before an uncountable noun to indicate a type of that noun or an instance of that noun. For example:

• We were driving in a dense fog. (An instance where the fog was dense.)

• The sand was bright pink, not a sand I'm familiar with. (An unfamiliar type of sand.)

• The air was filled with a most beautiful music. (A beautiful form of music.)

Dew, mist, fog, rain, snow are meteorological phenomena. "A rain/fog/mist/dew/snow " can be used to describe a single meteorological occurrence of them. (So "We drove through a fog on our way to San Francisco." sounds O.K. to me. Here, adding the article a implies that it wasn't foggy the whole trip.) This doesn't work with hail, lightning, or thunder, because these phenomena are violent enough that one occasion of these is called a hailstorm, lightning storm, or thunderstorm.