Let me explain my primitive understanding of a capacitor.
In electrostatics, a conductor containing accumulated charges attracts opposite charges in a conductor that's separated by an insulator, this setup is called a capacitor.
While studying transmission lines, we associate a capacitance between the two lines or line and ground etc. But how is this possible, don't we need charges to accumulate to attract charges on the other conductor or ground? If the transmission lines are carrying current how do charges accumulate? The root of the question seems to be "Do current-carrying wires produce an electric field outside in addition to the magnetic fields?" If the answer is yes, then this electric field might attract the opposite charge in the other conductor, but I'm not sure.
well, you're studying transmission lines, so you definitely know Maxwell, and you also know that electrostatics is not a model you can model the transmission line with.
In the book I'm reading currently Stevenson and Grainger, the expression for capacitance between two lines in a single phase 2 wire system is found just like finding the capacitance between two oppositely charged straight long conductors placed in parallel. I'm not able to understand why this is possible, is there no need to account for the current at all?
I found a gif on wiki,
Is this the answer? The bunching up of electrons causes a capacitance?