Why is an air mass unlikely to form over the rocky mountains of north america

The mountains can and will block airflow from higher pressure systems that come in from a coast and won't combine to nake storms

Geothermic gradient is the rate of increasing temperature with respect to increasing the depth in the earths interior. away from tech tonic plates boundaries, it is about 25-40 c/km (72-87 degrees f/mi) of depth near the surface in most of the world.