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Precipitation

Precipitation. Precipitation. Any form of moisture that falls from the sky. The main forms are. Rain Snow Sleet Hail. Rain. Liquid precipitation Varies in size Normal raindrops between 0.5 to 5 mm Less that 0.5 mm drizzle. Snow. May be Small pellets Individual crystals or

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Precipitation

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  1. Precipitation

  2. Precipitation Any form of moisture that falls from the sky

  3. The main forms are • Rain • Snow • Sleet • Hail

  4. Rain • Liquid precipitation • Varies in size • Normal raindrops between 0.5 to 5 mm • Less that 0.5 mm drizzle

  5. Snow • May be • Small pellets • Individual crystals or • Crystals that combine to form snowflakes • Large at temps near 0 C and become smaller at lower temperatures

  6. Sleet • When snow falls through a layer of freezing air near the surface

  7. Damaging Precipitation http://www.chaseday.com/hailfall.htm

  8. Hail • Solid precipitation in lumps of ice • Spherical or lumps • Forms in cumulonimbus clouds

  9. Remember Convection!!!! • Hot, less dense air rises • Requires daytime heating • Patches of sunlight help Updrafts (in red) rise as ground surface is heated by the sun above ambient air temperatures (blue).

  10. Formation of Hail Intense Updraft Strong Updraft

  11. Hail Formation • Hail stones form by accretion • Small hail gets caught up in the updraft and goes to the top of the cloud where it receives another layer of ice • This repeats until the hail cannot be supported by the updraft and it falls

  12. Hail requiresstrong updrafts to form • For the smallest hail to form, an updraft of around 36 to 54 km/h (24-34 mph) is required. • golf-ball size (1 3/4 inch diameter) -- require updrafts of around 88 km/h (55 mph) to form. • Softball-size hail involves updrafts exceeding 160 km/h (100 mph).

  13. “like driving on ball bearings” http://www.chaseday.com/hailfall.htm

  14. Record Hail • Record hail fell in Coffeyville, KS • diameter 14.4 cm (5.67 inches) • Credit: NOAA Photo Library

  15. Punching the core

  16. Hail Sizes • Pea6.4 millimeters (0.25 in) • Dime17.9 millimeters (0.70 in) • Penny19 millimeters (0.75 in) • Nickel21.2 millimeters (0.83 in) • Quarter24.26 millimeters (0.955 in) • Half dollar30.6 millimeters (1.20 in) • Walnut38 millimeters (1.5 in) • Golfball44 millimeters (1.7 in) • Tennis Ball64 millimeters (2.5 in) • Baseball70 millimeters (2.8 in) • Grapefruit108 millimeters (4.3 in) • Softball114 millimeters (4.5 in)

  17. Measuring Precipitation • A Rain gauge is used to measure liquid precipitation

  18. Doppler Radar • Doppler radar is a key forecasting tool • Based on the Doppler principle also used with light and sound

  19. All weather radars send out radio waves from an antenna. Objects in the air, such as raindrops, snow crystals, hailstones or even insects and dust, scatter or reflect some of the radio waves back to the antenna. • All weather radars, including Doppler, electronically convert the reflected radio waves into pictures showing the location and intensity of precipitation. • By Jack Williams, USATODAY.com

  20. Remember the meteorologist saying the wind is blowing towards or away from the radar • Used to indicate rotation in a thunderstorm which could indicate a tornado forming

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