Writelike Charles Dickens: The fog in Bleak House

Like the first sentence, it's a short, punchy, and fragmentary.

Like the second sentence, it imagines an axis and then shows us two contrasting poles.

In this instance, the axis is north-south, and the contrasting poles are the marshes in the north and the heights in the south. 

"How do you know it's north-south?"

By looking up Essex and Kent on a map! (And there's Greenwich, which will come up in the next snippet, in the middle.)

If you lived in London, this axis would be obvious—but even if you don't, you still get the sense of 'from one end to the other' in the description.

So, for your variation imagine an axis, even if it might not be obvious to your reader what it is.

The snippet has a simple parallel structure:

• The intrusion: Repeating the name of the intrusion.
• Location: A simple prepositional phrase to locate the intrusion.
• Comma: In this snippet, the fragments are joined by a comma. Why not a semicolon? Basically, because these fragments are short and don't need the extra breathing room of a semi-colon to help the reader follow them.

Notice how in the sweat example we changed the scale of the axis from human (head-toe) to city (sky-ground) in order to go to more interesting locations.

By now you might be noticing how the repetition and rhythm in each of these snippets creates a musical effect, sort of like the way a background score draws you into a movie.

Notic how the effect isn't created only through repeating the word 'fog', but also by the variations in shorter and longer sentence and clause length throughout.