Alto-stratus clouds are a common sight in the sky, particularly in cooler climates. These clouds appear as a flat, gray layer that often covers the entire sky. They are formed at an altitude of around 2 to 7 kilometers and are composed mainly of water droplets. Synonyms for alto-stratus clouds include layer clouds, middle clouds, and gray skies. These clouds are often confused with cirrostratus clouds, which are thinner and create a halo effect around the sun or moon. Alto-stratus clouds are generally associated with mild weather, but they can also indicate the approach of a storm. Understanding the different types of clouds can help us predict weather patterns and plan accordingly.