precipitation precipitation any form of moisture that falls from the sky
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PrecipitationPrecipitation
PrecipitationPrecipitation
Any form of moisture Any form of moisture that falls from the skythat falls from the sky
The main forms areThe main forms are
RainRain SnowSnow SleetSleet HailHail
RainRain
Liquid precipitationLiquid precipitation Varies in sizeVaries in size Normal raindrops between 0.5 to 5 Normal raindrops between 0.5 to 5
mmmm Less that 0.5 mm drizzleLess that 0.5 mm drizzle
SnowSnow
May be May be Small pelletsSmall pellets Individual crystals Individual crystals
or or Crystals that Crystals that
combine to form combine to form snowflakessnowflakes
Large at temps Large at temps near 0 C and near 0 C and become smaller at become smaller at lower temperatureslower temperatures
SleetSleet
When snow falls When snow falls through a layer of through a layer of freezing air near freezing air near the surfacethe surface
Damaging PrecipitationDamaging Precipitation
http://www.chaseday.com/hailfall.htm
HailHail
Solid precipitation Solid precipitation in lumps of icein lumps of ice
Spherical or Spherical or lumpslumps
Forms in Forms in cumulonimbus cumulonimbus cloudsclouds
Remember Convection!!!!Remember Convection!!!!
Hot, less dense Hot, less dense air risesair rises
Requires daytime Requires daytime heatingheating
Patches of Patches of sunlight helpsunlight help
Updrafts (in red) rise as ground surface is heated by
the sun above ambient air temperatures (blue).
Formation of HailFormation of Hail
Hail FormationHail Formation Hail stones form by Hail stones form by
accretionaccretion Small hail gets caught up in Small hail gets caught up in
the updraft and goes to the the updraft and goes to the top of the cloud where it top of the cloud where it receives another receives another layer of layer of iceice
This repeats until the hail This repeats until the hail cannot be supported by cannot be supported by the updraftthe updraft and it falls and it falls
Hail Hail requiresrequires strong updrafts to formstrong updrafts to form
For the smallest hail to For the smallest hail to form, an updraft of form, an updraft of around 36 to 54 km/h (24-around 36 to 54 km/h (24-34 mph) is required. 34 mph) is required.
golf-ball sizegolf-ball size (1 3/4 inch (1 3/4 inch diameter) -- require diameter) -- require updrafts of around 88 updrafts of around 88 km/h (55 mph) to form.km/h (55 mph) to form.
Softball-sizeSoftball-size hail involves hail involves updrafts exceeding 160 updrafts exceeding 160 km/h (100 mph).km/h (100 mph).
““like driving on ball like driving on ball bearings”bearings”
http://www.chaseday.com/hailfall.htm
Record HailRecord Hail Record hail fell in Record hail fell in
Coffeyville, KSCoffeyville, KS diameter 14.4 diameter 14.4
cm (5.67 cm (5.67 inches)inches)
Credit: NOAA Photo Library
Punching the corePunching the core
Hail SizesHail Sizes PeaPea6.4 millimeters (0.25 in)6.4 millimeters (0.25 in) DimeDime17.9 millimeters (0.70 in)17.9 millimeters (0.70 in) PennyPenny19 millimeters (0.75 in)19 millimeters (0.75 in) NickelNickel21.2 millimeters (0.83 in)21.2 millimeters (0.83 in) QuarterQuarter24.26 millimeters 24.26 millimeters
(0.955 in)(0.955 in) Half dollarHalf dollar30.6 millimeters 30.6 millimeters
(1.20 in)(1.20 in) WalnutWalnut38 millimeters (1.5 in)38 millimeters (1.5 in) GolfballGolfball44 millimeters (1.7 in)44 millimeters (1.7 in) Tennis BallTennis Ball64 millimeters 64 millimeters
(2.5 in)(2.5 in) BaseballBaseball70 millimeters (2.8 in)70 millimeters (2.8 in) Grapefruit108 millimeters Grapefruit108 millimeters
(4.3 in)(4.3 in) Softball114 millimeters (4.5 in)Softball114 millimeters (4.5 in)
Measuring Precipitation Measuring Precipitation
A Rain gauge is A Rain gauge is used to measure used to measure liquid liquid precipitationprecipitation
Doppler RadarDoppler Radar
Doppler radar is a Doppler radar is a key forecasting key forecasting tooltool
Based on the Based on the Doppler principle Doppler principle also used with also used with light and soundlight and sound
All weather radars send out radio All weather radars send out radio waves from an antenna.waves from an antenna.Objects in the air, Objects in the air,
such as raindrops, such as raindrops, snow crystals, snow crystals, hailstones or even hailstones or even insects and dust, insects and dust, scatter or reflect scatter or reflect some of the radio some of the radio waves back to the waves back to the antenna. antenna.
All weather radars, All weather radars, including Doppler, including Doppler, electronically convert the electronically convert the reflected radio waves into reflected radio waves into pictures showing the pictures showing the location and intensity of location and intensity of precipitation. precipitation.
By Jack Williams, By Jack Williams, USATODAY.com USATODAY.com
Remember the meteorologist saying the wind Remember the meteorologist saying the wind is blowing towards or away from the radaris blowing towards or away from the radar
Used to indicate rotation in a thunderstorm Used to indicate rotation in a thunderstorm which could indicate a tornado formingwhich could indicate a tornado forming