Cirrus clouds are high-altitude cloud formations characterized by their thin, wispy appearance. They are primarily composed of ice crystals and typically occur at altitudes above 20,000 feet. Their formation is influenced by the mixing of dry, cold upper-atmospheric air with warmer air masses. Due to the extremely cold temperatures at these altitudes, the condensation process immediately leads to the deposition of water vapor as ice. Cirrus clouds often streak across the sky, reflecting sunlight and sometimes appearing iridescent, and their presence can indicate large-scale atmospheric shifts, such as the influence of the upper-level jet stream.