“Why is there a cloud around the top of Mt. McLoughlin when there are no other clouds in the sky?”
Logos Charter School
Mountains cause what’s called Orographic Lifting, which means air is forced to rise due to the mountain. When air rises it cools at the adiabatic lapse rate and when a cloud forms over a mountain it means that the temperature of the air parcel cooled to the dewpoint and condensation was able to occur. On the opposite side of the mountain you get sinking air, which warms at the dry adiabatic lapse rate so that the temperatures and dewpoint grow further apart. On a stable day no other lifting occurs in the atmosphere and so you can get a single cloud to form over a mountain while no other clouds are in the sky. This can occur in the unique way of a lenticular cloud, which looks like a spaceship floating over a mountain.