Sigh, precisely what you don't want to know is what answers your question! As I said earlier: Your confusion comes from looking at an utterly wrong picture. Calculate the field yourself and then draw the field lines, etc. You find these pictures in any good E+M book. Look for "Hertzian dipole solution". This is the most simple time-dependent field you can have!
pleco said:
I'm not setting up conditions or deciding how charges are moving, just trying to interpret the diagram. I'm looking at any instant in time where blue vectors are depicted as vertical arrows pointing upwards.
Forget the diagram. It's misleading!
pleco said:
I'm not asking for any numerical values now, only about general properties and basic relations: greater, less or equal, positive or negative.
Well, you cannot answer these questions, if you do not define the conditions under which the electromagnetic field is created. So nobody can answer your question.
pleco said:
It doesn't make sense to me either. As I remember Ampere's and Faraday's law it's moving E field that creates B field, not changing, just moving, and moving E fields are electric current. So basically it's electric currents that create B field depending on current density. In return changing magnetic field can create an electric current by making E fields move, but I never thought B field can change E field or create new ones.
There are four local (!) equations governing the entire business of electromagnetism. That are Maxwell's equations. Those equations have solutions, giving the electromagnetic field (consisting of six components, usually written in terms of two three-dimensional vector fields, \vec{E} and \vec{B}) as being caused by electric charge and current distributions, which can be clearly interpreted by a cause-effect relation: The charge-current distribution is the source of the electromagnetic field, which is connected to the sources by retarded integrals, which takes into account that the em. waves travel always with the speed of light (in a vacuum). There cannot be faster-than-light cause-effect relations due to the causality structure of relativistic spacetime, and electrodynamics is a relativistic theory.
If you wish, you can artificially write the electric field in terms of the magnetic field, using Faraday's Law, but if you plug in the solution of the magnetic field, you see that it this is a very complicated, non-local and not expclicitly causal expression. Thus, it is not possible to interpret the electric field as being caused by a time varying magnetic field. In the same way you can express the magnetic field in terms of the current density and the time derivative of the electric field by solving the Ampere-Maxwell Law, and again you don't find an easily interpretable cause-effect relation.