What it does
Zarka is a disjunctive that almost always leads into Segol. The two form a tight phrase unit: when you see Zarka, expect Segol within a few words. Together they bracket a major sub-phrase, usually in the first half of a long verse.
Where it appears
Only appears in verses long enough to need a Segol pause. The position of Zarka relative to Segol is somewhat flexible, sometimes immediately before, sometimes two or three words earlier.
How to remember it
Zarka means "scattering" or "throwing." The mark is a curving hook above the letter, like a small wave or hook being thrown. Think of the curve as the throw motion that lands at Segol a moment later.
Example from the Torah
Bamidbar 7:89
In Bamidbar 7:89, a long verse describing Moshe entering the Ohel Moed, Zarka sets up the Segol on אִתּוֹ֒, framing the first major clause.
Hear the melody
A synthesized rendering of the melodic shape, not a vocal recording. For a baal koreh's voice on a full aliyah, PocketTorah is a great free resource.
Hand signal (simanim)
Often confused with
Zarka and Segol always travel together. Zarka is the lead-in; Segol is the landing. They are different marks but inseparable as a phrase unit.