Which of the following is not a form of precipitation?

The form of precipitation that is not included in the given options is "dust". Precipitation refers to any form of water that falls from the atmosphere and reaches the surface of the Earth. This can include rain, snow, sleet, and hail, all of which are forms of water in different states. Hail is a type of precipitation that falls as small pellets of ice during thunderstorms. Snow is another type of precipitation that forms when water vapor in the atmosphere freezes and falls to the ground as ice crystals. Dew, on the other hand, is not considered a form of precipitation because it does not fall from the atmosphere. Rather, it forms when water vapor condenses on surfaces during the night when the temperature drops. Finally, dust is not considered a form of precipitation because it is not made of water. Rather, it consists of tiny particles of soil, dirt, and other materials that are blown around by the wind. While dust can fall from the atmosphere and settle on surfaces, it is not classified as a form of precipitation. Therefore, the correct answer is "dust".