Now take that same thin metal sheet, bend it over a curved surface, and strike it with a hammer.
The point you would be striking is called the tangent.
You are taking the same force of impact, and instead of dispersing it onto a surface the size of the hammer’s head, you are now focusing all that energy on a single point.
To put in lamen terms: imagine pushing your finger against a tabletop vs. a knife blade (I know. I cringed just thinking of it too).
This strike along this smaller surface area results in SPLITTING the piece of thin metal. This split is a breach. This is what can happen to hip & ridges when impacted by hail.