I can't keep them all straight. A clarinet is what most folks call a trumpet, a trumpet looks identical except for one or two bigger loops. A clarion is something I haven't encountered - except it is another name for a medieval trumpet (probably with a short bell since they mention it as a "shrill" instrument).
Clarion: "a small shrill trumpet or bugle"
Short horn gives a "shrill" sound, larger horn gives a mellow rounder sound - the other extreme is the French horn. Probably why the French Horn is so slow.
Now that I think about it. The atmosphere probably represents a very low impedance load with a low resonant frequency, the French horn couples to the low impedance a trumpet is mismatched to a higher impedance. The Trumpet can bounce around and do its own thing while the French Horn or Tuba, or Sousaphone, is mired in trying to move the whole atmosphere.
Interesting