Lenticular clouds are peculiar enough that, for years, they’ve…

Lenticular clouds are peculiar enough that, for years, they’ve been mistaken for other things – often UFOs. These lens-shaped clouds tend to form near mountainous terrain, where air gets forced up and over the topology. If there’s a drop in temperature as the air rises, water can condense out to form the cloud. Once the air sinks, it warms enough that condensation is no longer possible. The result is a cloud that appears to stand still even though the air is moving. In reality, the cloud is constantly reforming from the moisture of incoming air. Lenticular clouds can form as a single layer, or they can form stacks like the one pictured above in Boulder, Colorado. They may seem odd, but they’re actually fairly common. If you live near hills or mountains, keep an eye out for them!  (Image credit: @bayouowl; via Ilya L.)