Thin gossamer cirrus clouds generally indicate a change in weather, usually preceding fronts that move from west to east. They form about 5 miles or more above the earth and are composed of ice crystals. They are commonly called is mares’ tails due their shape and form which changes constantly due to strong upper level winds or wind sheer. A curtain of snow or ice crystals often precipitates from them, but it soon evaporates. Late in the day they can produce spectacular sunsets.