The discussion on this thread, at a web site supposedly read by Torah-observant Jews, shows very little influence of Torah. The answer to the question – what is the significance of this or that kipa – should be answered by reference to the texts of the Torah, Talmud, and the written record of the gedolim.
Instead, most of the responses posted so far are anecdotal or bad, unscientific “surveys” of observed behavior.
Can anyone give a Torahic answer to the question posed?