Precipitation Precipitation Water evaporates from every surface on

Precipitation

Precipitation • Water evaporates from every surface on Earth • This water eventually returns to the surface • This process is called Precipitation – Any form of water that falls from clouds and reaches Earth’s surface

Precipitation • Not all clouds produce precipitation • Cloud droplets or ice crystals must grow heavy enough to fall through the air • Grow by colliding and combining with other droplets

Types of Precipitation • 1) Rain – Most common kind of precipitation – Must be 0. 5 mm in diameter to be considered rain – Smaller drops of water is called drizzle; even smaller drops are called mist • 2) Sleet – Rain drops freeze into solid particles of ice as they fall – Must be smaller than 5 mm in diamter

Types of Precipitation • 3) Freezing Rain – Rain that freezes when it touches the surface • 4) Snow – Water vapor converted directly into ice crystals in a cloud – Endless number of shapes and patterns, all with six sides or branches

Types of Precipitation • 5) Hail – Round pellets of ice larger than 5 mm in diameter – Only forms inside cumulonimbus clouds during thunderstorms – Grow as they fall to the ground

Modifying Precipitation • Long periods of unusually low precipitation are called droughts • Can be very harmful and cause hardship • One method used to modify precipitation is cloud seeding – Tiny crystals of silver iodide and dry ice are sprinkled into clouds from airplanes to create precipitation