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Hail

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  Hail by the Numbers High Winds by the Numbers Tornadoes by the Numbers  

Hail is frozen precipitation in the form of balls or irregular clumps associated with thunderstorms. It is formed as small pieces of ice are held aloft by an updraft within the thunderstorm, and grow by accretion as they collect supercooled water droplets. They can grow anywhere from the size of peas to softballs, and 3/4 inch is the severe criteria. Since a strong updraft is needed to support such weight, hail is typically produced by very strong thunderstorms. In fact, to support a grapefruit sized stone, an updraft wind speed of approximately 100 mph is needed.

Below is a table relating qualitative descriptions of hail to diameter and updraft wind speed.

Hailstone
Size
Measurement Updraft
in. cm. mph m/s
BB < 0.25 < 0.64 < 24 < 11
Pea 0.25 0.64 24 11
Marble 0.5 1.3 35 16
Dime 0.7 1.8 38 17
Penny 0.75 1.9 40 18
Nickel 0.88 2.2 46 21
Quarter 1 2.5 49 22
Half Dollar 1.25 3.2 54 24
Walnut 1.5 3.8 60 27
Golf Ball 1.75 4.4 64 29
Hen Egg 2 5.1 69 31
Tennis Ball 2.5 6.4 77 34
Baseball 2.75 7 81 36
Tea Cup 3 7.6 84 38
Grapefruit 4 10.1 98 44
Softball 4.5 11.4 103 46

Hail Sizes Compared to Other Objects
Hail Sizes Compared to Ruler

 

 

 

Hail by the Numbers>>