HELENA — Lenticularis clouds, more commonly known as lenticular, are quasi-stationary clouds that appear to be standing still. However, the air around these clouds is often very turbulent and fast-moving, giving the cloud its smooth shape. As air travels on the surface of the earth, obstructions are often encountered, with mountains being a major disrupter of airflow.
Montana is full of mountains, and under the right conditions lenticular clouds fill up our big sky.
Lenticular clouds are created when an obstruction like a mountain gets in the way of the flow of moist air. The mountains disrupt the airflow, creating turbulence and causes air to rise and fall in a wave-like pattern on the leeward side of the mountain. As this air rises and meets a layer of cooler air, the air condenses and forms a cloud.
As long as this air is forced over the mountain, the cloud continues to form at the crest of the air-wave so to speak. This lift can happen directly over a mountain or several miles downstream from the mountain. The Continental Divide often creates the chinook arch cloud, a form of a mountain wave or lenticular cloud.
Lenticular clouds have been said to be mistaken for UFO's as many of these clouds have the shape of a flying saucer or a lens. Because lenticular clouds rarely form over low-lying or flat terrain, many people may have never seen one before and don't know that they can exist. But here in Montana, we are often under lenticular invasion.