Desert phenomenon can include a variety of natural occurrences, such as mirages, dry lakes, and dust storms. A MIRAGE is an optical illusion caused by atmospheric conditions, which makes it appear as if there is a pool of water in the desert. A dry lake is a depression in the desert that contains no water, but may fill with water during periods of heavy rain. A dust storm is a strong wind that carries large amounts of dust and sand, reducing visibility and creating a hazardous environment.