Kelvin Hemholtz Clouds

Here are some Kelvin Hemholtz clouds(not sure how to spell them) that I took on Mother's Day outside the office front door. Here is the definition of such clouds:

Kelvin-Helmholtz instability can occur when velocity shear is present within a continuous fluid or when there is sufficient velocity difference across the interface between two fluids. The theory can be used to predict the onset of instability and transition to turbulent flow in fluids of different densities moving at various speeds. Helmholtz studied the dynamics of two fluids of different densities when a small disturbance such as a wave is introduced at the boundary connecting the fluids.

Basically, this means the there is a lot shear in the atmosphere. A pilot definitely wouldn't want to fly near these! A few hours after these pics were taken, Billings and especially areas just east, got hit with severe thunderstorms with 60+ mph winds and golf ball size hail. Click on the green text (not sure why there) to enlarge the pic.