1. PRECIPITATION DRIZZLE: small, uniform liquid droplets RAIN: liquid droplets…larger than drizzle

2. SLEET: small ice pellets that form when rain drops fall through cold air and freeze (frozen rain).

4. GLAZE: super-cooled raindrops that freeze on contact with solid objects; ICE STORM

6. SNOW: ice crystals remain frozen.

7. HAIL: hard, layered round ice pellets. Leave cloud frozen, remain so until landing.

11. Causes of Precipitation Supercooling –(ice process) –Ice crystals & supercooled water droplets mix in cloud tops. –When they are large enough, they fall. –Most Ohio rainfall… Collision-coalescence –(warm cloud process) –Liquid droplets collide & stick together. –Gravity takes over when they grow large. –…those big, fat, warm raindrops!

13. DOPPLER RADAR: Bounces radio waves off rain/snow. Works like sonar in water! Tells location, direction of movement, & intensity of precipitation.

16. Lake-effect snowstorms Land just downwind of the Great Lakes receive heavy snow each winter Localized snows of several feet can occur Buffalo, NY on Nov. 20, 2000 received its third largest 24-h snow (25 inches)

17. Buffalo 2000

19. More key processes As air crosses the lake, water evaporates and moistens the air Heat is also transferred from the air to the lake As the air heats, it becomes unstable and begins to rise and form cumulus clouds

20. Lake-effect processes Cumulus clouds form about halfway across the lake, growing in height and intensity closer to the lee shoreline As the air crosses the shore, it slows up owing to more friction

21. Ascent on the lee side of the lakes Slowing of the winds causes low-level convergence with rising motion and further cloud development and precipitation on the lee side of the lakes