Cirrus clouds are high-altitude clouds that form above 20,000 feet in the atmosphere. They are thin and wispy in appearance, often resembling delicate strands of hair. These clouds are primarily composed of ice crystals due to the cold temperatures at such heights. Cirrus clouds typically indicate fair weather, but they can also signal that a change in the weather is coming. When they thicken and spread out, they may suggest an approaching storm or weather front. Observing cirrus clouds can help in predicting short-term weather changes.