Here is a nice summary on clouds basic, how they form, how they relate to air motions, their different shapes and what do they mean.

“Clouds are an ever-present feature of the earth’s atmosphere. Everyday, around the world, many different types of clouds are seen overhead. We often look at the clouds above us and try to imagine the shapes and figures that they resemble. But clouds tell us much more. They are visible signatures of the motion and conditions of the air in which they exist.

Clouds consist of tiny liquid water droplets or ice crystals or a combination of both. Because these particles are so small, even weak swirls of air movement can keep them suspended indefinitely. It is the multitude of tiny water particles, whether liquid or ice, that interacts with rays of light to make clouds visible.”

More at Environment’s Canada Project Atmosphere Canada.

Photo from StephenBrooks.org .