Mesh where no Links were before

Well it is cold enough and my radio signals are once again bouncing of the atmosphere connect the two furthest nodes together, see map. Is it coincidence that I just changed out one of the radio cards and started to get a new connection? The samething happened last year about this time. Mild weather in January follow by tremendous amount of radio skip. The question does occur why only two nodes? And is it truly radio skip or reflection from tall buildings in the area?

The new radio card sure boosted the power and the receiving such that a steady signal can be viewed. When I changed out the old 200mW radio card the signal fade to the point that it was not receiving or sending. Back in the Lab it is once again working properly.

If this was radio skip rather than reflection then all the nodes would start to try to mesh with each other. I believe this really is atmospheric combined with reflection. For example. I have two units that have a clear path between them but due to trees and small buildings they do not mesh. If it was atmosphere skip then these two nodes would start seeing each other. Currently they don't even detect the radio card signals (sigspy).

Connecting between two node that are reflecting off major structure is never good. Signals are not that consistent and tend to end up with an intermittent connection. Now saying this I do have numerous large building near me and some of my connections due reflect off these buildings. They are steady but the signal are never that strong.