Cirrus Clouds are high altitude, wispy clouds, seen in fine weather. Cirrostratus Clouds are made up of ice particles and form a halo around the sun. If a Cirrus filled sky darkens and turns to Cirrostratus it is a sign of rain or snow, depending on temperature. Altostratus Clouds form a greyish veil over the sun or moon. If they get darker and thicken, it is a sign that rain is on the way. Nimbostratus Clouds form low blankets of cloud and indicate rain or snow, lasting for several hours. Stratocumulus Clouds can form a lumpy mass covering the entire sky and may produce light rain, but usually dissipate by the late afternoon or evening. Stratus Clouds are low clouds that form a fog like layer and may produce drizzle.