A cloudy sky occurs when clouds cover a significant portion of the sky, blocking sunlight. These clouds can vary in type, including cumulus, stratus, and nimbus, each contributing to different weather conditions. A cloudy sky often indicates the possibility of precipitation, such as rain or snow, depending on the temperature and humidity levels. Clouds are formed when water vapor in the air cools and condenses into tiny water droplets or ice crystals. The thickness and density of the clouds can affect visibility and temperature, making a cloudy day feel cooler than a clear one. Observing a cloudy sky can provide insights into upcoming weather patterns.