Precipitation

1. Precipitation Another process brought to you by the water cycle

3. The Four Types of Precipitation • Rain (Freezing Rain) • Sleet • Snow • Hail

5. Rain • Can start as liquid water or ice. Ice melts as it falls, turning into rain. • Hits the ground as liquid water. • Rain drops start as a round drop. As it falls it becomes more like a hamburger bun, flattening out as it falls. • A raindrop can break into two drops as it spreads out.

6. Rain

7. Snow • Snow is formed when water vapor turns directly into ice without ever passing through a liquid state. This happens as water condenses around an ice crystal. • Snow can be ice pellets or snow flakes. As snow falls to the ground, it often melts on the warm surface of the Earth. If the surface of the Earth is chilled sufficiently it begins to pile up creating snow drifts. In some locations, such as mountains, these snow drifts can reach several feet in depth.

8. Snow

9. Sleet • Sleet refers to a mixture of snow and rain, as well as raindrops that freeze on their way down. • Sleet, unlike snow, is when raindrops pass through a liquid form before freezing. The result is that they are not light and fluffy. • Sleet bounces when it hits the ground.

10. Sleet

11. Freezing Rain • Freezing rain is sometimes called glaze. • Freezing rain happens when water droplets become super-chilled. They do not freeze in air, but rather freeze the instant they land on an object such as a road, or car. The result can make roads very slippery, and can cause car doors to become frozen shut.

12. Freezing Rain / Glaze

13. Hail • Hail is formed as nearly round balls of ice and snow. • Hail is formed, deep within cumulonimbus clouds. • There ice crystals form and begin to fall towards the Earth’s surface. As this happens, wind gusts pick up the ice crystals pushing them back up high into the clouds. As they begin to again fall down, they grow in size. Again, a wind gust might catch the growing hail stone pushing it back up high into the cloud. This may be repeated several more times, until the hail stone becomes too heavy for the wind to carry, causing it to finally fall. • True hailstones occur only at the beginning of thunderstorms and never when the ground temperature is below freezing. • Hailstones range in diameter from 2 mm to 13 cm • Larger hail can be very destructive. • Often several hailstones freeze together into a large, shapeless, heavy mass of ice and snow.

14. HailVideo of hail forming

15. Resources • http://commons.wikimedia.org • http://www.geography.hunter.cuny.edu/~tbw/wc.notes/5.cond.precip/sleet_formation.htm • www.unitedstreaming.com • http://www.kidsgeo.com/geography-for-kids/0100-atmospheric-moisture.php