We study properties of the tropical double Hurwitz loci defined by Bertram,
Cavalieri and Markwig. We show that all such loci are connected in codimension
one. If we mark preimages of simple ramification points, then for a generic
choice of such points the resulting cycles are weakly irreducible, i.e. an
integer multiple of an irreducible cycle. We study how Hurwitz cycles can be
written as divisors of rational functions and show that they are numerically
equivalent to a tropical version of a representation as a sum of boundary
divisors. The results and counterexamples in this paper were obtained with the
help of a-tint, an extension for polymake for tropical intersection theory.Comment: 29 pages, 16 figures. Minor revisions, to appear in Journal of
Algebraic Combinatoric