What is hail?
A: Hail is a form of solid precipitation.
It consists of balls or irregular lumps of ice, each of
which is called a what?
A: A hailstone.
Hail formation requires environments of strong, upward
motion of air within the parent thunderstorm (similar to tornadoes) and
lowered heights of what?
A: The freezing level.
In the mid-latitudes, hail forms where?
A: Near the interiors of continents, while, in the tropics, it tends to be
confined to high elevations.
There are methods available to detect hail-producing
thunderstorms using what?
A: Weather satellites and weather radar imagery.
Hailstones generally fall at higher speeds as they
what?
A: Grow in size.
Severe weather warnings are issued for hail when the
stones reach what?
A: A damaging size, as it can cause serious damage to human-made structures,
and, most commonly, farmers' crops.
Unlike ice pellets, hailstones are layered and can be
what?
A: Irregular and clumped together.
Hail is composed of what?
A: Transparent ice or alternating layers of transparent and translucent ice
at least 1 mm (0.039 in) thick.
Although the diameter of hail is varied, in the United
States, the average observation of damaging hail is what?
A: Between 2.5 cm (0.98 in) and golf ball-sized 4.4 cm (1.75 in).
Stones larger than 2 cm (0.80 in) are usually
considered large enough to do what?
A: To cause damage.
Hailstones can be very large or very small, depending
on what?
A: How strong the updraft is: weaker hailstorms produce smaller hailstones
than stronger hailstorms.
The more powerful updrafts in a stronger storm can do
what?
A: Keep larger hailstones aloft.
Hail forms in strong thunderstorm clouds, particularly
those with what?
A: Intense updrafts, high liquid water content, great vertical extent, large
water droplets, and where a good portion of the cloud layer is below
freezing 0 °C (32 °F).
A single hailstone may grow by collision with other
smaller hailstones, forming what?
A: A larger entity with an irregular shape.
In North America, hail is most common in what area?
A: The area where Colorado,
Nebraska, and
Wyoming meet, known as "Hail
Alley".
When does hail occur in this region?
A: Between the months of March and October during the afternoon and evening
hours, with the bulk of the occurrences from May through September.
What is North America's most hail-prone city with an
average of nine to ten hailstorms per season?
A: Cheyenne, Wyoming.
It is estimated that a hailstone of 1 cm (0.39 in) in
diameter falls at what rate?
A: At a rate of 9 m/s (20 mph), while stones the size of 8 cm (3.1 in) in
diameter fall at a rate of 48 m/s (110 mph).
Hailstone velocity is dependent on what?
A: The size of the stone, its drag coefficient, the motion of wind it is
falling through, collisions with raindrops or other hailstones, and melting
as the stones fall through a warmer atmosphere.
What is the largest diameter officially measured?
A: 7.9 in (20 cm) diameter, Vivian, South Dakota, 23 July
2010.
Where does the greatest average hail precipitation
fall?
A: Kericho, Kenya which experiences hailstorms, on average, 50 days
annually.
Hail can cause serious damage, notably to what?
A: Automobiles, aircraft, skylights, glass-roofed structures, livestock, and most commonly, crops.
Hail is one of the most significant thunderstorm
hazards to what?
A: Aircraft.
When hailstones exceed 0.5 in (13 mm) in diameter,
planes can be what?
A: Seriously damaged within seconds.
Hail is also a common nuisance to drivers of
automobiles doing what?
A: Severely denting the vehicle and cracking or even shattering windshields
and windows.
What are the most sensitive crops to hail damage?
A: Wheat, corn, soybeans, and tobacco.
Rarely, massive hailstones have been known to cause
what?
A: Concussions or fatal head trauma.
Hailstorms have been the cause of costly and deadly events throughout history.
Around the 9th century in Roopkund, Uttarakhand, India,
200 to 600 nomads seem to have died of what?
A: Injuries from hail the size of cricket balls.
