Precipitation is the result of a rise in temperature causing water to become a gas and to enter the atmosphere. The gas rises, and as it rises the gas begins to form cloud droplets. The droplets become heavy as additional gas evaporates into the atmosphere through the process of evaporation. Once the weight of the droplets exceeds the amount of water that can remain in the atmosphere, the droplets are released back to the earth as rain. Another form of precipitation occurs when the air cools and forms a condensed bond. The colder the water droplets get, and the closer the molecules are results in the droplets entering the earth as hail. Hail has the appearance of ice rocks and falls in varying sizes. Snow is also formed by the cold air condensing but not as tight a bond as hail. Instead, particles attach to the cooled water droplets and drift to the earth as snow. If weather conditions are cold but not cold enough to form snow, a mixture of rain and snow, known as sleet, will fall to the earth. Types of precipitation include, rain, hail, snow, and sleet.