Lenticular clouds can be one of the most majestic of all clouds a pilot will ever see while in flight. From a turbulence perspective, they are smooth more often than not and generally don't occur during the summer months. Lenticular clouds simply identify the presence of a gravity wave. Mountain waves are the most common form of a gravity wave. In order for mountain waves to form, they require a stable layer to exist above the ridge lines. When this occurs and the wind is generally perpendicular to the mountains, these gravity waves can form. If there is enough moisture, standing lenticular clouds can form at the crest of the wave.
But during the summer, instability dominates during the late morning into the early evening. If you see a bunch of cumuliform clouds over top of the mountains, there's a real good chance that the atmosphere is unstable and not conducive for mountain wave activity.
Here's proof of that. In this animated gif above that starts out just after sunrise, you'll notice that some standing lenticular clouds have formed in extreme northwest Wyoming and south-central Montana. They have a wispy look and feel. But as the heating of the day kicks in and cumuliform clouds begin to form, you'll notice that the lenticular clouds literally melt away and the debris gets carried off in the prevailing wind. Once the lapse rate turns from stable to unstable, this triggers the production of cumulus clouds which eliminates the mountain wave activity.
Most pilots are weatherwise, but some are otherwise.™
Scott Dennstaedt
Weather Systems Engineer
CFI & former NWS meteorologist
