Hail

Hailstorm
SignChunks of ice falling from the sky, during a rainstorm or thunderstorm.
TypeSevere
Cloud of originCumulonimbus
EffectExtreme damage, dents in metal
A large hailstone, about 6 cm (2.4 in) in diameter

Hail is a form of solid precipitation. It is distinct from ice pellets (American English "sleet"), though the two are often confused.[1] It consists of balls or irregular lumps of ice, each of which is called a hailstone. Ice pellets fall generally in cold weather while hail growth is greatly inhibited during cold surface temperatures.[2]

Unlike other forms of water ice such as graupel, which is made of rime, and ice pellets, which are smaller and translucent, hailstones usually measure between 5 millimetres (0.2 in) and 15 centimetres (6 in) in diameter. The METAR reporting code for hail 5 mm (0.20 in) or greater is GR, while smaller hailstones and graupel are coded GS.

Hail is possible within most thunderstorms as it is produced by cumulonimbus,[3] and within 2 nautical miles (3.7 km) of the parent storm. Hail formation requires environments of strong, upward motion of air with the parent thunderstorm (similar to tornadoes) and lowered heights of the freezing level. In the mid-latitudes, hail forms 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 weather satellites and weather radar imagery. Hailstones generally fall at higher speeds as they grow in size, though complicating factors such as melting, friction with air, wind, and interaction with rain and other hailstones can slow their descent through Earth's atmosphere. Severe weather warnings are issued for hail when the stones reach a damaging size, as it can cause serious damage to human-made structures and, most commonly, farmers' crops.

Definition

Any thunderstorm which produces hail that reaches the ground is known as a hailstorm.[4] Hail has a diameter of 5 millimetres (0.20 in) or more.[3] Hailstones can grow to 15 centimetres (6 in) and weigh more than 0.5 kilograms (1.1 lb).[5]

Unlike ice pellets, hailstones are layered and can be irregular and clumped together. Hail is composed of transparent ice or alternating layers of transparent and translucent ice at least 1 millimetre (0.039 in) thick, which are deposited upon the hailstone as it travels through the cloud, suspended aloft by air with strong upward motion until its weight overcomes the updraft and falls to the ground. Although the diameter of hail is varied, in the United States, the average observation of damaging hail is between 2.5 cm (1 in) and golf ball-sized (1.75 in).[6]

Stones larger than 2 cm (0.80 in) are usually considered large enough to cause damage. The Meteorological Service of Canada issues severe thunderstorm warnings when hail that size or above is expected.[7] The US National Weather Service has a 2.5 cm (1 in) or greater in diameter threshold, effective January 2010, an increase over the previous threshold of ¾-inch hail.[8] Other countries have different thresholds according to local sensitivity to hail; for instance grape growing areas could be adversely impacted by smaller hailstones. Hailstones can be very large or very small, depending on how strong the updraft is: weaker hailstorms produce smaller hailstones than stronger hailstorms (such as supercells).

Other Languages
Afrikaans: Hael
العربية: برد (هطول)
asturianu: Xarazu
Avañe'ẽ: Amandáu
Aymar aru: Chhijchhi
azərbaycanca: Dolu (yağıntı)
Bân-lâm-gú: Pha̍uh
беларуская: Град
беларуская (тарашкевіца)‎: Град
български: Градушка
bosanski: Grad (padavina)
català: Calamarsa
chiShona: Chivhuramabwe
Cymraeg: Cesair
Deutsch: Hagel
eesti: Rahe
Ελληνικά: Χαλάζι
español: Granizo
Esperanto: Hajlo
euskara: Txingor
فارسی: تگرگ
français: Grêle
galego: Sarabia
客家語/Hak-kâ-ngî: Pho̍k
한국어: 우박
Հայերեն: Կարկուտ
hrvatski: Tuča
Ido: Grelo
Bahasa Indonesia: Hujan es
ᐃᓄᒃᑎᑐᑦ/inuktitut: ᓇᑕᖅᑯᕐᓇᐃᑦ/nataqqurnait
íslenska: Haglél
italiano: Grandine
עברית: ברד
ಕನ್ನಡ: ಆಲಿಕಲ್ಲು
ქართული: სეტყვა
Kiswahili: Mvua ya mawe
kurdî: Zîpik
Кыргызча: Мөндүр
Latina: Grando
latviešu: Krusa
lietuvių: Kruša
lumbaart: Tempesta
magyar: Jégeső
Malagasy: Havandra
മലയാളം: ആലിപ്പഴം
मराठी: गार
მარგალური: კირცხი (ტაროსი)
Bahasa Melayu: Hujan batu
မြန်မာဘာသာ: မိုးသီး
Nāhuatl: Texihuitl
Nederlands: Hagel (neerslag)
नेपाली: असिना
日本語:
norsk: Hagl
norsk nynorsk: Hagl
occitan: Granissa
олык марий: Шолем
oʻzbekcha/ўзбекча: Doʻl
polski: Grad
português: Granizo
română: Grindină
Runa Simi: Chikchi
русский: Град
саха тыла: Тобурах
Scots: Hail
shqip: Breshëri
sicilianu: Gragnola
Simple English: Hail
slovenčina: Krúpa (ľadovec)
slovenščina: Toča
српски / srpski: Град (падавина)
srpskohrvatski / српскохрватски: Grad (padavina)
suomi: Rae
svenska: Hagel
Tagalog: Hail
татарча/tatarça: Боз яву
తెలుగు: వడగళ్ళు
тоҷикӣ: Жола
Türkçe: Dolu
українська: Град
vepsän kel’: Ragiž
Tiếng Việt: Mưa đá
walon: Gurzea
文言:
吴语:
粵語:
Zazaki: Torge
žemaitėška: Kroša
中文: 冰雹
Lingua Franca Nova: Graniza