The dramatic swooping clouds shown above are most likely glaciated altocumulus clouds illuminated by the setting Sun . They take on a rather fuzzy appearance probably because ice crystals have fallen into them from higher aloft, perhaps from dissipating cirrus clouds. Mid-level clouds , including altocumulus, are typically more sharply defined since they're composed of minute water droplets that readily evaporate . Note that at ground level the Sun has already dipped below the horizon . Photo observed from Murrieta, California , on October 28, 2015.